h o o - hawai‘i natural energy institute (hnei) · n. gaillard, c. heske, t.f. jaramillo,...

Hawai‘i Natural Energy Institute | School of Ocean & Earth Science & Technology University of Hawaiʻi at Mānoa, 1680 East-West Road, POST 109 • Honolulu, HI 96822

Phone: (808) 956-8890 • Fax: (808) 956-2336 • www.hnei.hawaii.edu

OBJECTIVE AND SIGNIFICANCE: As the amount

solar and storage integration increases in Hawaiʻi,

accurately capturing the impact of weather variability

and uncertainty is critical. In addition, with the

relatively small number of generating units on

Hawaiʻi’s grid, correlated outages and maintenance

events can significantly decrease reliability. The

objective of this work conducted by HNEI, in

collaboration with Telos Energy, was to develop

novel methodologies and tools to properly evaluate

system risk and the likelihood of capacity shortfalls

in high percentage renewable grids by

probabilistically simulating solar variability,

generator outages, and storage availability.

KEY RESULTS: A novel methodology to capture the

impact of solar variability, generator outage, and

storage availability on the reliability of high

percentage renewable grids was developed. A 21-year

dataset of solar irradiance and production profiles as

well as detailed probability distributions of generator

outages and maintenance schedules were developed

to allow application of this methodology to the

Hawaiʻi grids. The methodology captures inherent

solar variability, outlier weather events, and the

impact of generator outages. This new analysis

technique helps answer key questions for power

system planning that are missed by traditional

resource adequacy analysis such as:

• How much solar, storage, and thermal capacity is

required to maintain grid reliability?

• What is the effect of increased forced outages and

maintenance schedules on reliability?

• How much legacy thermal capacity can be

retired?

• How do multi-day low solar and extreme weather

events affect reliability?

BACKGROUND: Historically, production cost

analyses used to model economic dispatch of utility

generation sources typically focus on modeling hour-

to-hour and sub-hourly solar variability across a

single weather year. As battery storage is deployed in

quantities that impact grid operations, the challenge

of sub-hourly variability of the solar resource

becomes less important. Instead, periods of

challenging operations due to extended periods of low

solar output may occur. When these challenging

periods of low solar resources are concurrent with

generator failures, unserved energy may result. This

occurs when there is not enough capacity to serve

load. This issue may be particularly acute for

Hawaiʻi’s grids, which have relatively few, large

generators relative to the size of the load. This risk to

system reliability is expected to become more serious

as Hawaiʻi’s fossil fleet ages as more frequent outages

and maintenance events, increasing the likelihood of

concurrent events.

Traditional power system planning evaluates weather

risk and generator outages via resource adequacy

analysis rather than hourly production cost analysis.

This traditional resource adequacy analysis leverages

stochastic, probabilistic assessments of risk (weather

and generator outages), to determine the likelihood of

capacity shortfalls. However, this analysis is limited

because it does not capture chronological dispatch of

the power grid, but instead evaluates snapshots in

time, such as peak load hours. This inability to

capture chronological dispatch is likely to miss

significant events when evaluating systems with high

levels of energy limited resources, such as battery

storage and demand response.

The increasing importance of weather uncertainty and

generator outages, combined with the need to

accurately simulate storage and demand response,

requires novel methodologies and tools to properly

evaluate system risk and the likelihood of capacity

shortfalls. Under this activity, a new model to capture

the stochastic nature of grids with a high penetration

of variable renewable generation has been developed

and used to analyze capacity reliability of the Hawaiʻi

grids.

PROJECT STATUS/RESULTS: To address the

evolving challenges of system reliability on the

Hawaiʻi grids at high levels of solar and storage

integration, HNEI and Telos Energy developed and

applied novel grid modeling techniques and tools to

stochastically evaluate system operation across many

years of historical weather data and potential

generator outages. The project includes the

development of a detailed, Hawaiʻi-specific,

historical weather database. Weather conditions were

simulated over the past 21 years using National

Renewable Energy Laboratory’s (NREL) National

Solar Radiation Database (NRSDB). Combining the

weather data with solar PV plant-specific

Hawaiʻi Natural Energy Institute Research Highlights Energy Policy & Analysis

Stochastic Modeling for High Renewable Grids



information, such as location, DC:AC ratios, tracking

systems, etc., resulted in unique sub-hourly power

production profiles for each existing and proposed

solar PV project in Hawaiʻi. The figure below

illustrates the system-wide variability in monthly

generation (top) and an example of a single year’s

rolling weekly average of solar generation relative to

the 21-year average (bottom).

The methodology incorporates the historical weather

data for chronological solar production profiles and

then simulates grid performance for those years

against a series of randomly selected generator

outages and maintenance events. In the analysis

conducted to date, 21 years of historical solar data and

up to twelve random outage profiles were used

resulting in a matrix of 252 Monte Carlo samples,

each analyzing a full 8,760 hour year of chronological

operation. The result is the probability of a capacity

shortfall across nearly 2.5 million hours of grid

operation.

This process allows for the calculation of

conventional resource adequacy metrics, like Loss of

Load Expectation (LOLE), Loss of Load Hours

(LOLH), and Expected Unserved Energy (EUE),

along with typical production cost metrics like cost of

generation and curtailment. It also accurately captures

battery utilization and state-of-charge as well as better

incorporating storage scheduling, which inherently

increases capacity margins in some hours (charging)

in order to reduce risk in others (discharging).

In addition to the traditional resource adequacy

metrics like LOLE and LOLH that only characterize

the frequency of capacity shortfalls, the stochastic

analysis developed under this project provides

additional information, such as the size and duration

of events. This ability to characterize size, frequency,

and duration of reliability events offers the

opportunity to tailor mitigations to meet grid needs.

This allows for a more effective comparison between

mitigation technologies and operational responses,

such as battery energy storage, demand response, and

fossil capacity additions for reliability. For example,

battery energy storage and demand response may be

preferred options to mitigate short duration events,

whereas fossil generation or long-duration storage

will be required for longer duration events.



The new modeling techniques and tools outlined in

this report were developed to allow more accurate and

higher fidelity analysis of the need for capacity and

risks of unserved energy as the Hawaiʻi grids

transition to increasing levels of solar and battery

storage. This tool is being used to evaluate issues,

such as the reliable retirement of fossil generators, the

value of demand response, and battery storage for

capacity grid services, as well as the role of long-

duration storage for future power systems. These

topics are covered in separate projects in the Energy

Policy and Analysis section.

Funding Source: Office of Naval Research; Energy

Systems Development Special Fund

Contact: Richard Rocheleau, [email protected]

Last Updated: November 2020

https://www.hnei.hawaii.edu/projects/#policy


mailto:[email protected]



OBJECTIVE AND SIGNIFICANCE: As the Hawaiʻi

grids transition to high penetrations of solar plus

storage to meet generation needs, conventional

stability tools that utilize a limited number of

snapshots of operations expected to show worst-case

conditions (i.e. an evening peak load) cannot capture

the range of grid conditions that are important to

evaluate on high percentage-renewable grids.

The objective of this activity, conducted in

collaboration with Telos Energy, was to develop a

new tool to evaluate grid stability over the entire

range of operations expected throughout the course of

a year. Evaluating grid risk at every hour of the year

enables grid planners to understand both the

magnitude and duration of risk to the grid, which

gives valuable context for informing mitigation

decisions. A second objective of this activity was to

integrate both stability and cost production into one

tool, with a significant improvement over traditional

tools that cannot co-optimize production cost and grid

stability.

KEY RESULTS: The HNEI team has successfully

developed a new screening tool that quantifies the

stability risk to the grid using a probabilistic approach

across all 8760 hours of grid operation instead of just

at preselected conditions of expected risk. This

technique yields probability distributions of the

frequency excursions for grid events such as loss-of-

generation. This new tool provides a more

comprehensive means for assessing stability of the

Hawaiʻi grids as conventional thermal generation is

retired and replaced by variable renewables systems.

The accuracy of this new tool was calibrated using the

full dynamic model of the Oʻahu grid and validated

against the typical transmission planning snapshots as

described below.

BACKGROUND: Typical utility grid planning

processes only evaluate a limited number of grid

conditions for dynamic stability, sometimes as few as

two or three “worst-case” snapshots (i.e. summer

peak, spring light-load conditions) from each

planning scenario. This traditional approach provides

limited information for today’s modern grids with

high penetrations of variable renewable resources and

storage because (1) the “worst-case” periods are

shifting and no longer obvious and (2) this approach

provides no indication of how often the grid is

exposed to the “worst-case” conditions, which is

critical in understand how to best mitigate issues that

arise.

To overcome these limitations, the HNEI team

developed and validated a new tool to evaluate the

stability and performance of the grid probabilistically

across all 8760 hours of the study year for each

scenario. This enables a comprehensive, yet easy-to-

understand view of how system risk changes as the

grid evolves.

PROJECT STATUS/RESULTS: The new tool enables

an analysis that is both broad and deep by combining

the wide range of realistic grid operating conditions

over the course of an entire year (from PLEXOS) with

the detailed dynamic behavior of the grid during

major grid events (from PSSE). The core of the tool


Integrated Stability and Cost Production Analysis



is a simplified dynamic model of the island power

system. This simplified model is then calibrated using

the detailed dynamic model from PSSE. This

calibrated, grid-specific model then uses inputs from

the production cost tool (PLEXOS), such as the total

thermal generation online, renewable generation, and

energy storage reserves to estimate the grid frequency

excursion for each hour of the simulation assuming

loss of the largest single generator on the grid. This

methodology is shown schematically in the figure on

the previous page.

The output of the tool, the frequency nadir, is

captured to show the stress on the grid and the impact

to customers. The frequency nadir is the minimum

frequency that is reached after the loss of generation

event. Lower values of frequency nadir indicate

higher levels of grid stress and greater likelihood of a

blackout or the need for load shedding or blackout.

To quantify customer impact, the probability of load

disconnection due to the under-frequency load-

shedding scheme on the grid is reported. To more

easily visualize these results, the frequency nadir and

load-shedding metrics are presented as probability

distributions that show the probability of reaching a

certain level of grid stress (frequency nadir and load-

shedding) over the course of a year for a given mix of

generation resources. This is shown in the figure

below, where the frequency nadir from 8,760

individual dynamic simulations can be represented as

a single probability distribution curve. By running

multiple future resource mixes that consider different

penetrations of solar + storage, the probability

distributions can be plotted to show the trends in

dynamic stability as the grid becomes increasingly

renewable.

As indicated in the schematic, this new tool is fully

integrated with PLEXOS allowing the results of the

dynamic stability simulations to be fed back to

PLEXOS, where the scenarios and/or the grid

operations can be adjusted to achieve desired levels

of grid stability, such as a maximum value of load-

shedding or a minimum allowable frequency nadir.

This is fundamentally different than traditional

techniques where system cost is optimized first

without regard to stability, then adjustments to the

grid that are needed for grid stability reasons are made

second, which leads to a suboptimal resource mix.

Based on the desired stability objectives, operational

parameters such as generation commitment decisions,

generation retirement and replacement scenarios,

battery scheduling and utilization, and demand

response assumptions can all be adjusted individually

or in combination.

This tool has been applied to the island of Oʻahu to

assess grid stability with high solar + storage

integration and evaluate the risk of customer

disconnection and grid black-out for near-term

scenarios including the retirement of AES and the

installation of Stage 1 PV+BESS projects. The results

are detailed in the project summary “Oʻahu Grid

Stability with High Solar + Storage Integration”.

The tool has been benchmarked against the full

dynamic model of Oʻahu as represented in PSSE for

four different grid conditions, including the

maximum and minimum loads during daytime and

nighttime periods (see figures on following page). In

each case, the largest single generator is suddenly

disconnected and the grid frequency is over-plotted.

The focus of the validation is on matching the

https://www.hnei.hawaii.edu/wp-content/uploads/Oahu-Grid-Stability-with-Integration.pdf

https://www.hnei.hawaii.edu/wp-content/uploads/Oahu-Grid-Stability-with-Integration.pdf



frequency nadir, which is considered the most

important grid stress metric for loss-of-generation

events and directly corresponds with load-shedding

on Oʻahu. It is acknowledged that the dynamic

response of the grid predicted by the tool after the

frequency nadir occurs is often not accurate. This is

because the response of the grid after the nadir is

dependent on many other dynamics (thermal

generator governor dynamics) that are not modeled.

These post-nadir dynamics are not modeled because

they are not significant factors in the response of the

grid prior to the nadir. It is the period of time prior to

the nadir that is the focus of this analysis because this

period is most critical for the survivability of the grid

and most indicative of grid stress and customer

impact.

The loss-of-generation events are only one type of

challenging grid event that grid operators and

planners must assess. Other challenging events

including short-circuit (fault) events, particularly

with low grid strength, which occurs when there are

high levels of generation from inverter-based

resources and few conventional plants online. This

method and analysis tool can be adapted to evaluate

these risks as well, which is expected to be critically

important for Oʻahu, Maui, and Hawaiʻi in the near

future.








OBJECTIVE AND SIGNIFICANCE: The AES Hawaiʻi

coal plant, the largest power plant on Oʻahu is

scheduled to retire in 2022. This retirement will

decrease the amount of dispatchable fossil capacity

available to the utility by more than 10%. The

objective of this study was to evaluate the ability of

proposed solar + storage resources to maintain grid

reliability with the pending AES coal plant

retirement. The results of this analysis are being

briefed to the Hawaiʻi Public Utility Commission

(PUC) and other stakeholders and are expected to

have important implications for power system

planning and policy for Oʻahu.

KEY RESULTS: Stochastic analysis, using the tools

developed by the HNEI-Telos Energy team (see

project summary “Stochastic Modeling for High

Renewable Grids”), that included the annual

variability of the solar resource over 21 years and a

variety of fossil plant outage profiles was conducted.

It was determined that the AES retirement is likely to

increase reliability risks, with increased likelihood of

loss of load events (LOLE). This could occur even if

Stage 1 solar + storage resources are fully deployed

and would be considerably worse if there are delays

in project commissioning. However, reliability is

maintained or even improved once Stage 1 and a

relatively small fraction of the Stage 2 solar + storage

projects are completed. While standalone storage was

found to effectively mitigate the reliability concerns,

other potentially less costly solutions were also

identified.

BACKGROUND: As the Hawaiʻi grid transitions to

higher percentages of renewable energy, new

resources are being integrated to not only provide

renewable energy, but also to provide the grid

services conventionally provided by AES and other

fossil generation. Combining solar and battery

storage resources allows solar energy to be shifted

from the middle of the day when there is surplus

renewable generation to evening peak load hours after

the sun has set. This allows the dispatchable hybrid

solar + storage projects to replace and retire

conventional fossil generation such as the AES coal

plant. The ability of the Oʻahu grid to replace large

amounts of energy currently supplied by thermal

generation with energy supplied by solar + storage

systems without significant curtailment is described

in more detail in the “Curtailment and Grid

Services with High Penetration Solar + Storage”

project summary. The inclusion of storage into these

systems offers the opportunity for them to provide

grid services, one of which is capacity – or the ability

to provide energy when it is required for reliability.

However, there are limitations that arise due to the

reliance on the variable solar resource, energy

limitations of the storage, contractual limitations for

battery charging, and uncertainty of generator

outages.

The AES coal plant is an independent power producer

with a long-term Power Purchase Agreement (PPA)

with Hawaiian Electric Company (HECO) that

expires in 2022. HECO does not plan to renew the

PPA. In addition, SB 2629 enacted in 2020 bans coal-

fired generation in Hawaiʻi after 2022, ensuring the

AES retirement. Given the relatively short timeframe,

the most likely replacement resources are the

announced Stage 1 solar + storage projects (137 MW

of solar, 548 MWh of storage), potential standalone

battery storage, and demand response.

The Stage 1 projects were originally proposed to be

completed in 2022, concurrent with the AES

retirement. However, as of October 2020, some of the

projects are delayed between 6-13 months, potentially

pushing out their availability to after the legislatively

mandated AES coal retirement. An additional 287

MW of solar, 1,275 MWh of battery storage was

awarded in the “Stage 2 RFP” that could also provide

replacement capacity for the AES retirement, but

most of these projects, as proposed are not expected

to be online until 2023 or later. As a result, the timing

of the AES retirement and replacement solar +

storage projects could jeopardize system reliability in

the short run.

To overcome this concern, HECO has awarded – also

through the Stage 2 RFP – a PPA for the 185 MW

battery energy storage project to be located in

Kapolei. This project is being developed as a direct

replacement for the AES capacity. However, given

the amount of solar + storage resources going in

through the Stage 1 and Stage 2 renewable

procurements, there may be significant surplus of

capacity available shortly after the AES retirement.

It is therefore important to understand the extent to

which hybrid solar + storage resources can reliably


Grid Reliability with AES Retirement

https://www.hnei.hawaii.edu/wp-content/uploads/Stochastic-Modeling-for-High-Renewable-Grids.pdf

https://www.hnei.hawaii.edu/wp-content/uploads/Stochastic-Modeling-for-High-Renewable-Grids.pdf

https://www.hnei.hawaii.edu/wp-content/uploads/Curtailment-and-Grid-Services.pdf

https://www.hnei.hawaii.edu/wp-content/uploads/Curtailment-and-Grid-Services.pdf



replace fossil generation, while also considering the

technical and contractual limitations of the resources.

The Stage 1 projects consist of four solar + storage

hybrid projects, totaling 137 MWac of capacity.

These hybrid projects are DC coupled, where the

battery storage and solar PV share a common DC:AC

inverter and grid connection (see figure below). As

indicated in the figure, each of the Stage 1 projects

has an overbuild of the PV panels of approximately

40% and includes 4 hours of storage relative to the

nameplate rating of the plant. Energy generated by the

plant can go directly onto the grid or via the battery,

but the total output of the plants at any given time is

limited to the AC rating of the plant.

In addition, contractual restrictions on the operation

of the Stage 1 projects requires charging of the battery

to come predominately from the solar resource, as

opposed to the grid, for the first five years of the

project. These restrictions intended to secure the

maximum benefit from the federal investment tax

credit have been included in the analysis.

As described in the “Stochastic Modeling” summary,

novel modeling techniques were developed to

accurately account for the chronological operations of

storage, solar variability, and generator outages. This

new stochastic methodology combines the disciplines

of resource adequacy analysis with operational

production cost modeling to better simulate grid

reliability with high penetrations of solar, storage, and

demand response. These methodologies have been

applied to the Oʻahu grid to determine if solar +

storage systems could maintain reliability when AES

is retired.

PROJECT STATUS/RESULTS: The stochastic

methodology previously described was used to

evaluate the reliability of near-term changes on the

Oʻahu grid, specifically the retirement of the AES

coal plant and successive buildout of large amounts

of utility-scale solar + storage resources. Six levels of

solar + storage buildout, up to an additional 426

MWac of solar with 1,833 MWh of battery storage,

representing the full buildout of recently awarded

Stage 1 and Stage 2 projects were evaluated.

Each case was analyzed across 252 random draws

(replications) of chronological dispatch, representing

21 years of solar data and 12 outage profiles. The

output of the analysis included the number, the

magnitude, and the duration of the capacity shortfall

events that occur when there are not enough available

resources to serve load. This methodology was

repeated across eight cases, one of which represents

the current system (Base Case), one with AES retired

without any replacement capacity, and the six

additional cases with AES retirements and

incremental additions of solar + storage resources up

to the equivalent capacity of the Stage 2 buildout.

The matrices on the following page summarize the

number of hours of unserved energy for two of the

eight cases, the Base Case, and a case assuming the

AES retirement and full build out of the Stage 1

projects. For each case, the number of hours of

unserved energy for each of the 252 random draws of

solar and unit outages are shown. As the matrices

indicate, many draws do not have any capacity

shortfall events, but on average, the number of hours

with outages increases by 82% when AES is retired

and only replaced with Stage 1 resources.

Interestingly, the results summarized in these

matrices indicate that even with an increased reliance

on solar-based resources, there is no clear dependence

on which year of solar data is used. This suggests that,

at this level of solar + storage integration, annual

weather variability, and extreme weather events do

not significantly affect system reliability. As

discussed in more detail below, the results show that

even in years that do have capacity shortfalls, the

majority of outages are only between 1-4 hours

durations.



In contrast to the lack of dependence on the solar year,

a strong dependence on the outage draw is indicated.

While the total amount of outages used as input to the

analysis was consistent across the random draws, the

timing and characteristic of the outages changes

across the random samples. This is strong evidence

that the timing and correlation of fossil generator

outages is the primary cause of capacity shortfall

events.

For each case, the results of the 252 random draws are

summarized into a single metric, the average LOLE

value across all the draws. Additional metrics are

quantified, including loss of load expectation

(LOLE), which summarizes average days per year

with a capacity shortfall event; loss of load hours

(LOLH), which summarizes the average number of

hours per year; and expected unserved energy (EUE),

which provides an average amount of unserved

energy (MWh) per year. The figure below shows the

average LOLE for each of the eight cases. LOLE (y-

axis) is plotted against increasing solar + storage

adoption (x-axis). Low values represent lower risk of

capacity shortfall. The dot on the lower left y-axis

represents the Base Case, the current system before

the AES retirement and without additional solar +

storage. The line represents system reliability after

the AES retirement with increasing amounts of solar

+ storage.



It should be noted that while the LOLE metric

provides a quantitative measure of system risk, the

absolute number is very sensitive to changes in

assumptions. Because the Oʻahu grid is a small

system, changes to the underlying outage rates and

planned outage schedules can significantly change

the reliability metrics. It is therefore important to use

consistent assumptions across the cases and evaluate

the relative differences across cases rather than focus

on the absolute level of reliability.

While the figure on the previous page highlights

unacceptable reliability with the AES retirement

without additional solar + storage, much of that loss

of reliability is recovered with the installation of the

Stage 1 solar + storage. The figure below with an

expanded y-axis allows better comparison of the

current system against the solar + storage replacement

cases. As shown, relative to AES retirement without

the addition of solar + storage, while much of the loss

in reliability caused by the retirement of AES is

recovered when the Stage 1 projects are included, the

modeled reliability is still nearly twice that of the

original baseline condition with AES operating. The

chart also shows that partial deployment of the Stage

2 projects in addition to the Stage 1 is sufficient to

bring the system back to the same level of reliability.

This finding is important. It indicates that, with

close to a one-to-one capacity swap, the hybrid

solar + storage resources can be effective and

reliable replacement resources for a coal fired

generator. While solar + storage resources can

reliably replace baseload coal, the system will need

more capacity than just the Stage 1 projects. The

results show that 166 MW of solar + storage (13%

more than Stage 1) is sufficient to replace 185 MW of

fossil generation (8% less capacity). In this analysis,

because solar + storage systems are highly modular,

made up of many discrete components, the analysis

assumed there is no failure mode likely to cause a

major loss of production like a steam turbine

generator that can lose 185 MW of capacity in a single

outage. More investigation of potential transmission-

related outages is needed to determine if there is risk

of single failure modes that could create an outage of

a full solar + storage facility. The potential for solar +

storage outage rates would increase the reliability risk

and require even more capacity to replace AES.

In summary, with the addition of as little as 30% of

the Stage 2 solar + storage projects, capacity

shortfalls are eliminated altogether. This indicates

that with Stage 2 implementation, there is sufficient

surplus capacity available to the grid, negating the

need for a standalone battery.

On the other hand, the results also indicate that project

cancellations or delays in the Stage 1 projects would

increase reliability risk, potentially significantly. For

example, if 50 MW of projects are delayed, which

represents only one of the Stage 1 projects, the

projected probability of a capacity shortfall doubles.

This clearly shows the need for a mitigation plan

to ensure project delays do not further erode

reliability.



Conventional resource adequacy metrics currently

used by the utility are limited, typically reported only

as the probability of a capacity shortfall event

(LOLE). Additional information that characterizes

the size, frequency, and duration of capacity shortfalls

is important to ensure mitigations are right sized for

the reliability needs of the system. This allows the use

of energy limited resources like demand response and

battery energy storage to provide key grid services.

These additional metrics are accessible via the

stochastic analysis used for this work.

The figure below provides a probability distribution

for capacity shortfall durations for the Base Case and

the full build out of the Stage 1 projects with AES

retired. The figure on the left shows the probability of

an outage of a specified duration while the figure on

the right shows the cumulative probability function.

These results show that nearly all events, with Stage

1 installed, are four hours or less, with more than half

of all shortfall events limited to less than two hours.

This means that a short duration energy storage or

demand response resource, used sparingly, can

effectively improve reliability, eliminating the need

for additional fossil generation.

The ability of limited energy standalone batteries and

demand response was evaluated to quantify their

ability to mitigate these short duration reliability

risks. A series of simulations were conducted adding

incremental demand response and battery storage

capacity to the system. This was done assuming 50%

of Stage 1 projects were installed and again assuming

full buildout of the Stage 1 solar + storage.

• Standalone Storage: The standalone storage was

configured to represent the proposed Kapolei

energy storage project, at 185 MW, 565 MWh (3-

hour duration). A scaled down, 60 MW

configuration, was also evaluated. Neither

configuration was assumed to have restrictions on

charging.

• Demand Response: Two types of demand

response programs were evaluated. One program,

which represents limited flexibility, evaluated 60

MW of demand response with 1-hour duration

(60 MWh per day), a maximum number of 40

calls per year, and could only be utilized on

weekdays from 8am to 9pm. This is indicative of

HECO’s current “Fast DR” program. A more

flexible demand response option with energy

duration to 2-hours (120 MWh), and no time of

day restrictions was also evaluated.

Results of these cases indicate that even a modest

amount of new resources can substantially improve

reliability. With Stage 1 fully deployed, a 60 MW

demand response or energy storage asset would make

the grid twice as reliable as the current system. Even

with only a 50% partial buildout of Stage 1,

approximately 60 MW of battery or demand response

would significantly improve reliability compared to

the PV + storage alone, although more would be

required to reach current reliability levels. This

finding is important, as it indicates that at current

levels, solar + storage, demand response, and

battery storage all provide approximately 1-for-1

replacement capacity for fossil generation and are

roughly equivalent from a capacity perspective.



Across both cases, the addition of 185 MW of

standalone storage is significantly more capacity than

is required to meet reliability requirements.

However, it should be noted that the 1-for-1

equivalency of energy limited resources will not

continue indefinitely. Saturation of these resources is

likely and their ability to replace fossil will diminish

at higher penetration levels of solar + storage. The

capacity value of energy limited resources at very

high penetration is evaluated further in the “Capacity

Value of Storage with High Penetration of PV and

Storage” project summary.

These results show that these additional resources for

reliability are rarely called on, indicating that a

resource that is only available several days a year can

yield significant reliability benefits (see left figure

below).

One of the most important factors impacting

reliability of a power system is the expected outage

rates of the generating equipment. This is especially

true for small, islanded power grids where concurrent

outages of generators can have a large effect on

reliability. This applies to both planned maintenance

and unexpected failures (forced outages). Oʻahu’s

installed capacity is 44 years old on average, with 260

MW of capacity over 60 years old. In addition, the

older steam generator technology was not designed to

cycle and ramp regularly in response to wind and

solar variability.

In 2016, there was a significant increase in the

maintenance and forced outage rates for the HECO

fleet, which is presented in the figure on the right.

While this step change can be attributed to increased

outages due to newly imposed environmental

constraints, it’s important to continue to track these

data. The results presented previously assumed a 12-

year average for forced and maintenance outage rates.

Additional cases using the more recent 5-year outage

rates have been initiated. Based on results to date,

key results and trends do not change. This has

implications for future planning. HNEI is working

closely with HECO to address these changes in

outages.

These results have important implications for power

system planning and policy for Oʻahu. Even with full

buildout of Stage 1 solar + storage resources, the AES

retirement could increase reliability risks. Recently

announced delays of Stage 1 projects indicate

buildout of Stage 1 by the time AES is retired may be

under 100MW. By the time Stage 2 is deployed, the

AES retirement reliability risk is fully mitigated.

While standalone storage would effectively mitigate

the reliability concerns other solutions may be in the

best interest of ratepayers. These may include:

• Accelerate Stage 1 and Stage 2 projects through

incentive payments, streamlined permitting,

and/or increased engineering budgets;

• Temporarily continue operation of AES, beyond

the current PPA term and legislative mandate;

https://www.hnei.hawaii.edu/wp-content/uploads/Capacity-Value-of-Storage.pdf





• Adjust maintenance schedules in 2023 by

deferring planned outages and other elective

maintenance;

• Increase energy efficiency, demand response,

and behind the meter storage deployment;

• Contract temporary diesel gensets; and

• Temporarily adjust the reliability criteria, update

involuntary load shedding schemes, and make

outages as least disruptive as possible.








OBJECTIVE AND SIGNIFICANCE: The objective of

this activity was to evaluate the dynamic stability of

the Oʻahu grid after a sudden loss of the largest

generating unit. Specifically, the analysis was

intended to identify any potential concerns regarding

stability of the Oʻahu grid following the upcoming

retirement of the AES coal plant and addition of the

Stage 1 solar + storage projects.

As the Hawaiʻi grids are transformed to include large

amounts of solar and solar + storage, it is important

to understand the dynamic behavior of these systems.

An unstable response of the grid to such an event

could result in significant levels of load-shedding

with interruption of electric service to customers and

even a potential black-out of the entire Oʻahu grid.

KEY RESULTS: The new screening tool, described in

the “Integrated Stability and Cost Production

Analysis” project summary, developed for the

purpose of assessing dynamic grid stability for each

hour of an entire year (8,760 hours) of grid operations

was used to perform a stability screening analysis for

two scenarios; one with AES retired and a second for

the retirement of AES with the addition of the Stage

1 solar + storage projects. The results show that

dynamic frequency stability of the grid is improved

with retirement of AES. While the addition of the

Stage 1 projects slightly degrades the response

relative to AES without the addition of the Stage 1

projects, the response to the largest contingency event

further improves if the solar + storage Stage 1 projects

are configured to provide fast frequency response

(FFR). These results are discussed in more detail

below.

BACKGROUND: Events like a sudden loss of a power

plant challenge the stability of the grid because the

unexpected loss of generation throws the grid “off-

balance.” This is because generation and load must

always be balanced on any electric grid. When a

power plant suddenly goes offline, for instance, due

to a weather event or equipment failure, the result is a

generation deficit as the total load does not change

immediately after the event. The generation deficit

must be corrected in a matter of seconds in order to

avoid a blackout of the entire grid. This means that

resources on the grid must recognize the generation

deficit and begin responding in fractions of a second.

The two means of correcting the imbalance are

increasing power generation from other sources

and/or reducing load by disconnecting customers.

Another related grid event is a sudden loss-of-load,

where there is suddenly an excess of generation on the

grid that causes an imbalance that must quickly be

corrected to keep the grid stable and operating. In the

loss-of-load event, generation must be quickly

reduced to match load. Because it is generally easier

for grid resources to quickly reduce generation than

to increase generation, this analysis did not consider

loss-of-load events, but focused on the more

challenging loss-of-generation events.

Historically, the inertia from the generators in

conventional power plants provide an inherently

stabilizing dynamic response to such grid events by

immediately increasing power generation, while the

ability of inverter-based resources to provide a

stabilizing increase in power generation, depends on

the inverter’s controls. FFR is one example of a type

of inverter control function that supports the dynamic

response of the grid by quickly injecting or absorbing

additional power in response to changes in grid

frequency in order to quickly restore balance to the

grid. Furthermore, FFR does not require any external

communication (like a command from the grid

operator) to work. This means that grid resources,

both utility-scale and distributed, can have the

autonomy to respond quickly to emergency events to

keep the grid operating.

PROJECT STATUS/RESULTS: To determine the

impact of the changing generation fleet on grid

reliability (stability), the response of the grid to a

challenging, yet credible, grid event is studied. This

begins with the 8,760 dataset output from a

production cost simulation that contains the details of

grid operations (total load, generator dispatch, and

production of wind, solar, storage) for each hour of a

year for a given scenario analyzed. For each hour of

the dataset, a dynamic simulation is performed for the

loss of the single largest (highest-dispatched)

generator on the Oʻahu grid during that hour, using

the new screening tool. The loss of the single highest-

dispatched generator is selected because it is the

worst-case generation contingency considered in

transmission planning studies.


Oʻahu Grid Stability with High Solar + Storage Integration

https://www.hnei.hawaii.edu/wp-content/uploads/Integrated-Stability-and-Cost-Production-Analysis.pdf

https://www.hnei.hawaii.edu/wp-content/uploads/Integrated-Stability-and-Cost-Production-Analysis.pdf



The output from each dynamic simulation is a

measure of grid stress and customer impact resulting

from the loss of generation event. The “stress on the

grid” is quantified by the grid frequency nadir

(excursion from the nominal 60Hz), where lower

frequency nadirs (greater excursions) are indicative

of higher levels of grid stress, where the grid is closer

to a system-wide blackout. The customer impact is

quantified by the amount of load shedding due to the

under-frequency load-shedding scheme that was

triggered by the event. More grid stress (lower

frequency nadirs) result in greater customer impact

(more load shedding).

This analysis was performed for the following

scenarios:

• Today’s (2020) Oʻahu grid;

• The retirement of AES (2022);

• The retirement of AES with the addition of Stage

1 solar + storage projects (without FFR); and

• The retirement of AES with the addition of Stage

1 solar + storage projects (with FFR).

The scenarios with the Stage 1 solar + storage projects

were configured in two ways. The first assumed that

the plant’s inverters could not provide FFR by rapidly

injecting power to the grid after a contingency event.

The second assumed the plants could provide FFR

and help restore frequency by injecting power rapidly

(milliseconds) after an event. It should be noted that

the technology is capable of providing this response,

but the actual reserve provision is dependent on

contractual terms and inverter control settings.

Because the analytical tools simulate a potential

contingency event across every hour of the year, it

generates significant data – with over 70,000 values

across 4 scenarios – results are summarized as

probability distributions. Each curve shows the

likelihood of reaching a certain level of stress on the

grid or load shedding level, given a trip of the largest

generating unit at the time.

As shown in the next figure (top), the retirement of

AES and the addition of Stage 1 projects moves the

probability distribution to the right – an indicator of

improvement, since the greatest excursions move

closer to the nominal 60Hz value that utilities always

try to maintain and farther away from 57.0Hz where

the grid would black out. The companion figure on

the bottom shows that the amount of customer

disconnection (UFLS) moves to the left – closer to

zero, where no customers would be impacted by a

worst-case loss-of-generation event.

In comparing the blue and orange traces of the plots,

this analysis shows a significant improvement in the

dynamic stability of the Oʻahu grid for loss-of-

generation events with the retirement of AES. This

result is counter-intuitive because it is showing better

grid stability for a shift away from conventional

resources, which we know have a stabilizing impact

on the grid because of their inertia contributions.

Because AES is the largest single generator on Oʻahu

– with a potential loss of 200 MW of net load – it is

often the single largest contingency. Therefore, by

retiring AES, the largest generation contingency is

dramatically reduced, resulting in a more stable grid.



When AES retires, the largest contingency is reduced

to 140 MW loss of Kahe 5 or Kahe 6. This change

will help improve dynamic stability because the

emergency events will no longer be as severe,

regardless of any other potential benefits from the

Stage 1 solar + storage projects.

The addition of Stage 1 projects without FFR

following the retirement of AES shows a slightly

negative impact on the dynamic stability of the grid

for loss-of-generation events (when compared against

the case without the AES retirement and no Stage 1

projects), as shown by a comparison of the orange and

red curves in the plots. While this scenario is still

much better than the Base Case, it is slightly worse

than the AES retired case because the additional Stage

1 renewables is displacing other conventional

resources and not reducing the size of the worst-case

contingency.

However, the addition of Stage 1 projects with FFR

shows an improvement in grid stability over the

scenario with Stage 1 projects without FFR, as shown

by comparing the red and green traces of the plots. In

this case, the provision of FFR from Stage 1 projects

improves the dynamic stability of the grid such that

there is no negative impact to stability resulting from

the Stage 1 projects, as shown by the similarity of the

orange and green curves of the plots.

The shift away from conventional technologies and

towards inverter technology (solar + storage plants)

constitutes a major change in the way the electric

power grid responds to challenging grid events like

the sudden loss of a power plant on the grid. As the

system continues to evolve towards increasing

percentages of inverter-based technologies (solar,

storage, wind), the behavior (software-defined

controls) of the inverters will become increasingly

important to the dynamic stability of the grid. This

goes beyond simply enabling useful features like

FFR, but also ensuring correct tuning of those

features.

This new analysis tool will be applied to look at more

future scenarios that consider the addition of more

solar + storage (Stage 2) projects as well as the

retirement of additional conventional power plants

like Waiau 3 and 4 to inform stakeholders of risk to

grid stability and assess the benefits of grid-services

like FFR. In addition, a closer examination of the

inverter behavior is warranted to determine an

appropriate balance fast-response and stable

response, which is an inherent trade-off in inverter

controls.








OBJECTIVE AND SIGNIFICANCE: The Hawaiian

Electric Company (HECO), with approval from the

Hawaiʻi Public Utilities Commission (PUC), is

negotiating power purchase agreements (PPA) for

substantial amounts of utility-scale solar + storage

assets in Hawaiʻi. The design and operation of these

resources is expected to impact the ability to integrate

these new resources into the grid, their ability to

provide grid services, and on grid reliability. The

objective of this study was to assess the impact of

PPA structures and plant configurations on

curtailment when large amounts of solar + storage are

added to the grid and to identify how these solar +

storage resources could be leveraged to increase value

and flexibility.

KEY RESULTS: HECO is completing PPA

negotiations that will add large amounts of utility

scale PV, with the typical project having four hours

of storage, based on plant nameplate capacity. The

addition of storage to these future PV deployments

significantly reduces but does not eliminate

curtailment. Mitigations, such as the retirement of

AES and cycling of select steam units, that provide

additional “space” on the grid for variable renewables

was found to significantly reduce the risk of

curtailment. It was also found that curtailment likely

occurred due to lack of load in the evening and

nighttime hours, not a result of insufficient storage.

In addition, the current DC-connected systems and

PPA structures that limit charging from the grid to

achieve full tax credits may miss significant

reliability benefits. Infrequent charging from the grid

during rare events increases benefits to the system.

Additional analysis is being conducted to quantify

these potential benefits.

BACKGROUND: At the end of 2018, the Hawaiʻi PUC

approved eight utility-scale solar + storage projects

collectively referred to as “Stage 1.” These projects,

totaling 275 MWac of solar and 1,100 MWh of

battery storage, are expected to be operational by the

end of 2022. Of this total, 140 MW of solar with 558

MWh of storage is proposed for construction on

Oʻahu. In a second solicitation, referred to as “Stage

2,” HECO selected an additional seven solar + storage

projects, totaling approximately 500 MW solar and

2,150 MWh of storage statewide that includes up to

287 MWac solar and 1,275 MWh of storage on

Oʻahu. In addition to these projects, HECO is

currently soliciting proposals for up to 235 MW of

solar under their Community Based Renewable

Energy (CBRE) efforts that are likely to include

additional battery energy storage.

These changes are taking place against the backdrop

of other significant changes to the grid, notably the

retirement of the AES coal plant, the largest fossil

generator on the Oʻahu grid. As a result, it is

important to understand how the proposed solar +

storage projects can be optimally utilized to ensure

efficient grid operations in the future.

The primary use case of the proposed solar + storage

projects is to mitigate potential oversupply of solar

resources in the middle of the day and to shift energy

into evening peak and overnight periods. This

decreases the need for oil units to cycle on and off,

reduces peak load, offsets more expensive oil-fired

generation used during overnight periods, and

minimizes curtailment. Details of the battery charging

will depend on utility requirements and in some cases,

restrictions in the PPA agreements, but in general, the

optimal dispatch that minimizes total generation costs

shows that battery charges to near full capacity during

the day, then discharges during evening peak and

overnight hours. The battery then discharges more

during the morning load ramp and is near minimum

state-of-charge by the beginning of the next daytime

period.

Optimal economic dispatch shows that a significant

fraction of the solar energy goes directly onto the grid.

This is because any solar energy that cycles through

the battery will incur additional round-trip efficiency

losses of approximately 10 to 15%. As a result, if

there is available room on the grid for more PV, the

PV will flow directly to the grid, displacing oil-fired

generation at the time the solar is produced.

Additional constraints such as minimum state-of-

charge and use of the battery for grid services will

also impact the battery charging.

The figure on the following page illustrates the

potential operations of the Oʻahu grid over a two-day

period for two scenarios of solar deployment. The top

chart shows representative grid operations with the

addition of 800 MWac without storage while the

bottom chart shows the same two days with 3200


Curtailment and Grid Services with High Penetration Solar + Storage



MWh of storage included. In this example, all the

energy that is curtailed without storage can be

accommodated on the grid when storage is added. At

higher penetrations, this is not the situation.

PROJECT STATUS/RESULTS: To understand the

utilization of solar + storage at very high penetrations,

a series of grid simulations were conducted with

increasing blocks of solar capacity. Each block

comprised 200 MWac of PV (500 GWh annually),

with 800MWh of storage. Each block represents

approximately 6.5% of Oʻahu’s annual energy needs.

Blocks were added up to an additional 3500 GWh,

which, when combined with existing renewables

represented a 70% renewable share (~80% RPS).

The optimizations were conducted for two grid

configurations, representing different thermal

generation resource mixes. The first represents the

“Current Oʻahu Grid,” and includes all fossil

generating units currently in operation and must-run

operations for the baseload steam oil units. The

second represents a “Modified Oʻahu Grid,” in which

the AES coal plant is assumed to be retired and the

steam units can cycle on and off, providing increased

grid flexibility and more “room” for accepting

variable renewable energy onto the grid.

While storage will delay PV curtailments, it will not

eliminate them. As shown in the figure on the

following page, solar integration with AES still

operational results in significant curtailment even

when storage is included. With 1500 GWh of

additional solar, overall curtailment reaches 3.2%.

This curtailment increases to 20% of the total solar

generation when 3500 GWh are added. More

importantly, incremental curtailment of the last solar

added rises quickly from 7% for the third 500 GWh

block to just under 60% for the last block. With the

retirement of the AES coal plant and ability for the

baseload steam oil units to cycle offline or turn down

to lower loading levels, curtailment is greatly reduced

but not eliminated. Additional constraints may

change these results when reliability and grid services

are considered. The “Grid Reliability with AES

Retirement” project summary discusses in detail

potential reliability issues when AES is retired.

Two Days of Future Grid Operations, with and without Storage

https://www.hnei.hawaii.edu/wp-content/uploads/Grid-Reliability-with-AES-Retirement.pdf




As shown below, batteries on average cycle less than

one time per day under optimal operations, indicating

that curtailment is not, in general, driven by the lack

of available storage capacity but rather by “space” on

the grid to discharge during evening and overnight

periods. At a certain point, there is not enough load in

the evening to adequately discharge before the solar

generation starts again the next day. This may be

alleviated by cycling select steam units or with further

retirements, but this requires a more detailed

evaluation including a careful analysis of grid service

needs.

As noted previously, this analysis does not support

adding additional storage as a means to mitigate

curtailment. In fact, as shown in the previous figure,

the daily average cycles per day is less than one for

both grid configurations and for all additional blocks

of solar + storage. In this analysis, a battery cycle is

measured as the amount of round-trip energy that is

charged and discharged relative to the capacity rating

of the storage.

Under Current Grid assumptions, cycling duty of the

storage increases as PV increases through 2,000 GWh

of installed PV, but then decreases. This is attributed

to a lack of evening load to fully discharge before the

next day begins. While still averaging less than one

cycle per day with the AES retirement, battery usage

increases with increasing PV penetration. In this case,

the additional “space” on the grid resulting from the

AES retirement and steam-cycling allows more PV to

go directly to the grid and more efficiently uses the

available storage. Changes to load or load profiles as

may occur with the addition of electric vehicles (EV)

would likely modify this behavior.

The figure below, shows this from another

perspective. This figure shows the fraction of the

solar energy (aggregated for the year) that goes

directly to the grid, goes to the grid via the storage, as

losses in the system, and the amount that is curtailed.

As noted above, the additional “space” on the grid

resulting from the retirement of AES allows a larger

fraction of solar-generated energy to go directly to the

grid, reducing the fraction required to be stored for

evening with a substantial reduction in curtailment.

In Hawaiʻi, most battery installations will not be

standalone, but instead will be coupled with an

adjacent solar PV system with shared plant and

Solar Energy by End Use Average Daily Storage Cycles with

Increasing Solar + Storage Integration

0%

10%

20%

30%

40%

50%

60%

70%

500 1000 1500 2000 2500 3000 3500

Cu

rtai

lmen

t (%

of

Ava

ilab

le)

Solar PV (GWh)

Current Grid (incr)

Current Grid (avg)

Modified Grid (incr)

Modified Grid (avg)

Solar Curtailment with Increasing Solar + Storage Integration



transmission infrastructure similar to the trend seen

throughout the country. There are several other

reasons for this trend:

• Investment Tax Credit: As long as storage is

charged 75% from renewable energy it qualifies

for the ITC, which can offset up to 30% of the

initial capital cost;

• Shared infrastructure: Hybrid projects share the

same transmission infrastructure across both

solar and storage systems;

• Simplified procurement: Hybrid projects allow

utilities to bundle the procurement into a single

PPA and purchase the renewable energy and

storage services on a simple $/MWh basis,

streamlining the regulatory approval process;

and

While the hybrid configurations bring many

advantages, including those listed above, they can

also introduce both technical and contractual

restrictions that result in additional operating

constraints. Across North America, the majority of

solar + storage projects are developed in a DC-

coupled configuration because it captures additional

energy due to “clipping losses” attributed to high

DC:AC ratios and shared transmission

interconnection infrastructure. However, with

Hawaiʻi’s small, low inertia grids, there may be

additional benefits to AC coupling (see figure below).

Specifically, AC-coupled solar + storage projects

afford more flexibility for system operators as both

the battery storage and solar portions of the plant can

be used in parallel, effectively doubling the capacity

of the resource during critical time periods. This

could, for example, negate the need for additional

standalone storage.

Fast frequency response has the potential to be

especially valuable on the island’s grids. Preliminary

model results indicate that AC-coupling can provide

up to two times more reserve capability during mid-

day hours when system inertia is lowest and increase

the total reserve availability by up to 30% over the

year. HNEI is conducting additional analysis to assess

benefits that may accrue from alternative solar +

storage configurations as well as possible benefits

that may accrue if direct charge from the grid is also

implemented.

Based these results, it is clear that hybrid solar +

storage additions can provide significant value to

Hawaiʻi’s grids, both with the ability to shift solar

energy to evening and overnight periods and to

provide grid services.









this analysis was to evaluate the ability of battery

energy storage to reliably replace the aging fossil-

fired generation fleet in Hawaiʻi. Specifically, this

analysis quantified the capacity value and resource

adequacy benefits that energy limited resources

provide to the grid to answer the question, “can solar

and battery energy storage replace the capacity value

of thermal generation?” As the Hawaiʻi grids

integrate additional solar + storage resources, the

capacity value metric will be a primary factor in the

ability to retire the thermal generating fleet.

KEY RESULTS: The results of this analysis indicate

that storage systems can provide capacity for

reliability, supporting efforts to retire fossil

generation. This is based on stochastic resource

adequacy simulations using GE Multi-Area

Reliability Software (GE MARS) to evaluate system

reliability under hundreds of combinations of load,

weather, and generator outages. However, as seen in

the “Grid Reliability with AES Retirement” project

summary for the retirement of AES, while storage can

provide an effective one-to-one replacement at

modest levels of penetration, this work found that the

efficacy of storage to provide firm capacity saturates

with increasing penetration of storage or solar +

storage.

BACKGROUND: The average age of the oil-fired1

power plants in Hawaiʻi is 40 years with at least one

being over 80 years old, arguably the oldest

operational fossil power plant in the U.S. Many of the

plants are now operating well past their original

design life. As the grid transitions to increased wind

and solar energy, these plants are used less for energy,

but are still being relied on to provide grid services

and capacity, especially during periods of low wind

and solar production. These plants are also being

operated differently, cycling more often and ramping

more regularly. The combination of aging

infrastructure and increased flexibility demands are

leading to increasing generator outages and required

maintenance.

1 Includes low-sulfur fuel oil, diesel, and dual-fueled (diesel and biodiesel) generating units.

At some point, these generators will need to be retired

and replaced with newer technology. While wind and

solar can replace their energy contributions, a better

understanding of their ability to provide capacity

benefits is needed for long term planning.

Energy storage, either standalone or paired with solar,

is increasingly being used in Hawaiʻi and across the

industry to provide firm capacity and other grid

services. Many of these systems are currently planned

for deployment in Hawaiʻi. However, because storage

is an energy limited resource and hybrid solar +

storage projects are dependent on variable solar

energy resources, these resources do not necessarily

provide the same nameplate capacity benefits as fossil

generation.

PROJECT STATUS/RESULTS: To evaluate the energy

storage capacity value, referred to as the effective

load carrying capability (ELCC), a series of Monte-

Carlo resource adequacy simulations were conducted

using the GE MARS. This analysis evaluates

generator outages across hundreds of random draws

to determine the expected amount of availability

capacity and quantifies the number of unserved

energy events. Storage resources with different

hourly capacities were then added to the system. Load

was then added to the system until the original

reliability level was achieved. The amount of load

added, relative to the amount of storage, determines


Capacity Value of Storage with High Penetration of PV and Storage




the capacity value of the resource.

While early storage additions can effectively replace

thermal capacity, as illustrated in “Grid Reliability

with AES Retirement”, the results of this analysis

illustrate that the capacity value of storage saturates

as penetration increases.

• With increasing storage and load shifting, the

net-load curve starts to flatten, and each

subsequent reduction in peak load requires an

increasing duration of response, as illustrated in

the figure below.

• The state of charge of the storage can vary

depending on daily variability of the solar

resource.

• At high penetrations, system risk shifts to

periods of low solar output, which could last

multiple day because of anomalous, but well-

understood and historic, weather patterns.

This limits the role storage can have on the system as

a firm capacity resource as well as its ability to fully

replace the need for conventional thermal generation.

However, full capacity credit until 30% of peak load

can still provide valuable near-term opportunities for

storage to replace aging fossil capacity. To further

retire and replace aging capacity, it will require either

longer duration storage resources, a larger portfolio of

storage and demand response, or other forms of

renewable generation.

This work has produced the following publication:

2019, D. Stenclik, et al., “Energy Storage as a

Peaker Replacement: Can Solar and Battery

Energy Storage Replace the Capacity Value of

Thermal Generation?”, IEEE Electrification

Magazine, Vol. 6, Issue 3, pp. 20-26.





https://dx.doi.org/10.1109/MELE.2018.2849835







BACKGROUND: The Hawaiʻi Public Utility

Commission (PUC) is the regulatory body tasked

with reviewing and deciding on key investment

decisions, rates, and long-term planning of Hawaiʻi’s

investor owned utility, Hawaiian Electric Company

(HECO). They are also tasked with reviewing the

reliability of the electric power system and its

customers. At any point, there may be dozens of

dockets under review by the Commission, many of

which are based on highly technical and detailed

analyses.

The topics under review by the PUC are diverse and

multi-faceted. In the past, the PUC has been short-

staffed and does not have access to the same modeling

tools and skillsets typically deployed by the utility for

their long-term planning and docket filings. As a

result, having the ability to draw on the expertise of

HNEI, and their contractor Telos Energy, provides

independent third-party technical expertise to

augment the analyses being conducted at the

Commission. The flexible nature of this support

ensures that work can be deployed in a timely and low

cost manner relative to the use of other third-party

consultants. This collaboration with HNEI provides a

flexible option to quickly analyze both near-term and

long-term questions posed by the Commission.

Additionally, under Hawaiʻi Revised Statutes

(“HRS”) § 269-92, electric utilities in the state are

required to reach increasing levels of renewable

generation. Every five years, the PUC is required to

publish a report, pursuant to HRS § 269-95, that

monitors and measures compliance to the state’s

Renewable Portfolio Standards (RPS) targets. HNEI

is legislatively mandated to perform this analysis of

the RPS status every five years for the PUC. HNEI

has supported the PUC in a number of these types of

analyses since 2017. A number of issues related to the

integration of renewable energy technologies are

discussed in other project summaries located in the

Energy Policy and Analysis section. Other examples

of past support included a review of HECO’s

distributed energy resources (DER) Grid Service

definitions and the economic merits of HECO’s

standalone battery proposals.

This paper discusses four recent examples of HNEI

support to the PUC support:

• Tracking and analysis of the state’s RPS targets;

• The impact of COVID-19 on electricity use and

potential reliability challenges;

• Lifecycle analysis of greenhouse gases for

Hawaiʻi relevant generating technologies; and

• Analysis of the effective use of the bio-diesel

fuel contract at the new Schofield Barracks

power plant.

PROJECT STATUS/RESULTS:

RPS Analysis: In December 2018, HNEI delivered

its third RPS assessment to the PUC. The HNEI

assessment was the basis for the PUC report

submitted to the state legislature.

This report projected that HECO and Kauaʻi Island

Utility Cooperative (KIUC) were both on track to

meet, and likely exceed, the 2020 30% RPS target. In

2019, KIUC generated 56% of its electricity from

renewable energy – already exceeding the 2030 target

of 40% – and is on a plan to exceed the 70% 2040

target by the mid-2020s.

Hawaiian Electric Companies generated 28.4% of its

total annual sales from renewable sources in 2019 –

25.2% by HECO (Oʻahu), 34.7% by Hawaiʻi Electric

Light Company (HELCO) (Big Island), and 40.8% by

Maui Electric Company (MECO) (Maui County).

With the completion of the Oʻahu “Waiver PV” and

West Loch PV projects (157 MW of utility-scale solar

PV) and additional distributed rooftop PV, HECO

was projected to increase generation by a further 3-

4%, exceeding the 2020 target. This is despite the

shutdown of the Puna Geothermal Venture plant that

remains offline due to the 2018 lava eruption event.

Lower than anticipated load due to COVID-19 and

related quarantine restrictions should ensure

compliance with the 30% target.

Based on the assumed completion of the HECO

“Stage 1” and “Stage 2” solar + storage projects,

HECO was also reported to be on course to exceed

the 2030 RPS target of 40% by 2030. The percentages

of renewables for the Hawaiian Electric Companies

for years from 2008 and projections through 2025 are

shown in Figure 1.


Decision Support Services to the Hawaiʻi Public Utility Commission


https://puc.hawaii.gov/wp-content/uploads/2018/12/RPS-2018-Legislative-Report_FINAL.pdf



Figure 1. Hawaiian Electric Companies’ percentages of renewable energy by resource, 2008 to 2025.

COVID-19 Impact on Electricity Use: In this

analysis, HNEI concluded that COVID-19

emergency measures had a significant impact on

electricity use in Hawaiʻi. HNEI and Telos Energy

reviewed hourly generation data to evaluate the

effects of COVID-19 and quarantine restrictions on

electricity demand. Using Oʻahu as an example,

analyses showed that commercial and industrial use

dropped, while residential use rose substantially. The

results illustrate that, in March 2020, the electricity

peak load on Oʻahu dropped from about 1000 MW to

about 900 MW, a drop of 10% (Figure 2, below).

Outcomes included findings that: less electricity was

used overall; less behind the meter generation was put

into the grid; and the “duck’s back” became more

pronounced due to the overall reduction of load. The

analysis identified potential risk of distributed

generation oversupply if rooftop solar generation was

high and load under quarantine measures continued to

drop.

The decrease in electricity demand during the middle

of the day has the potential to exacerbate impacts on

the grid related the “duck’s back.” That is, low loads

during the middle of the day could drop to levels

below minimum power operational requirements of

HECO’s thermal units, which, in turn, would require

significant changes in overall grid operations (Figure

3, on the following page).

While the Spring of 2020 saw numerous record-

setting renewable penetration levels (as a percentage

of load), grid reliability was not jeopardized. This is

largely because there was not a confluence such as

low load coinciding with peak renewable generation

Figure 2. Change in electricity demand following Stay-at-Home order.



of events such as low load coinciding with peak

renewable generation and HECO was able to manage

dispatch of the steam oil fleet. However, this analysis

was able to check, in a timely manner, if reliability

would be challenged.

Lifecycle Greenhouse Gas (GHG) Analysis:

Hawaiʻi has been in the forefront of integrating

renewable energy technologies into its energy mix. In

2008, the state launched the Hawaiʻi Clean Energy

Initiative (HCEI). The goal of this initiative was to

substantially reduce the use of fossil fuels. Since then,

there have been a number of modifications enacted

leading to the current RPS goal of 100% fossil free

energy use by 2045.

While some renewable energy generation

technologies do not emit CO2 at the point of use, there

are embedded emissions that are created during the

full life cycle of the technology. Therefore, a number

of steps must be evaluated to determine the emissions

that arise from the production (mining and

manufacturing), operation and maintenance, and

disposal/reuse of these technologies. In other words,

every facet of the any energy technology and resource

life cycle will have some GHG emissions, even if the

actual production of electricity does not produce any

GHGs.

For some renewable resources, like biomass and

biodiesel, large amounts of CO2 may be emitted at

time of generation, but depending upon the biomass

source, operations, and life-cycle assumptions,

considerable offset of these emissions is possible

through new plantings or sequestration.

Recently, the need to perform life-cycle analyses

(LCAs) for GHG emissions in Hawaiʻi has become

more important. The PUC, as part of its decision

making, is required to consider GHGs. A number of

lawsuits have emerged that require these types of

analyses. In late 2019, the PUC requested that HNEI

evaluate net life cycle GHG emissions for a number

of energy technologies and resources in order to

provide the PUC with a Hawaiʻi-specific quantitative

assessment of emissions from these systems. These

analyses will then be used to support the

Commission’s decision making. HNEI has completed

a comprehensive literature review of existing LCA

studies and selected those applicable for Hawaiʻi for

further evaluation.

HNEI is completing the requested assessment and

will soon convene a meeting of stakeholders from

Hawaiʻi and experts from the U.S. Department of

Energy’s (DOE) national laboratory system. Based on

available literature and additional analysis conducted

by HNEI, a wider than expected range of estimates

for lifecycle emissions was found. Even for well-

defined technologies, such as PV, substantial ranges

were found, partly due to variations in the technology

but largely due to variations in the assumptions

surrounding the manufacture of the components. For

other technologies, such as biomass and biofuels,

existing studies can provide general guidance, but

Figure 3. Implications of Quarantine minimum daily load on grid services.



variation in the type of feedstock, the conversion

technology, and the final disposition of waste – for

example, the re-growth of new biomass resources –

requires site-specific studies.

HNEI expects to convene the expert panel in early

2021 with a final report to the PUC in the first quarter

of 2021.

Evaluation of Biodiesel Generator at Schofield

Barracks: In 2018, the Schofield Generating Station

started operations. The plant is highly flexible, but

has a fuel contract that requires a minimum biodiesel

offtake each year and requirements on dual fuel

operations. The PUC requested that HNEI review the

fuel offtake requirements and evaluate potential

operating practices that could be implemented to

reduce system costs.

While the price of biodiesel is significantly higher

than diesel, a requirement of the contract for this

project is a minimum fuel offtake requirement. It was

recommended that the cost should be treated as a

fixed cost and not be considered when determining

Schofield dispatch decisions. Additionally, Schofield

is one of the most flexible and most efficient thermal

units on the system. It is therefore more economic to

utilize the entire biodiesel offtake and fuel blending

requirements so that the plant can later switch to

diesel fuel. This would allow HECO to capture all of

the flexibility and efficiency benefits of the plant

while meeting contractual requirements.

Funding Source: Energy Systems Development

Special Fund






OBJECTIVE AND SIGNIFICANCE: The Hawaiian

Electric Company (HECO) under guidance from the

Hawaiʻi Public Utilities Commission (PUC) has

initiated the Integrated Grid Planning (IGP) process

to determines the types of resources and grid services

the utility should invest in over the coming years. A

Technical Advisory Panel (TAP) has been established

to provide a third-party, technical, and unbiased

review of HECO’s modeling efforts to ensure it

implements best practices and novel techniques being

used in other regions. HNEI is currently chairing the

TAP, which consists of experts from around the

country. HNEI’s role as chair is in support of the PUC

in response to their request for HNEI to provide

leadership in this activity.

KEY RESULTS: HNEI’s involvement in the IGP and

its leadership role in the TAP ensures that HECO will

be able to move forward in addressing grid issues

related to increasing amounts of renewable energy,

which combines both distributed, behind-the-meter

generation, and utility-scale projects. Thus, in

addressing the IGP docket, HECO receives

independent and technical oversight from outside

experts. This helps ensure that the utility is using

industry-accepted methods, inputs, and assumptions.

Following an initial period in which the progress of

the IGP did not fully meet expectations, HNEI was

requested to assume an expanded role in supporting

the IGP initiative. This increased support has

included re-constituting the TAP membership,

working with HECO staff to revise their approach for

TAP meetings, and assistance in the review of

presentation materials to ensure that meetings are as

effective as possible. In addition, due to issues that

have arisen in Working Groups and with the

Stakeholder Council (Figure 1), HNEI has also taken

an expanded role in its participation in these

activities.

This approach has been confirmed by the PUC

request to HECO for the TAP to play a more

substantive role in advising HECO as it moves

forward with its integrated grid planning activities.

This approach was confirmed in a May 2020 letter

from HECO to the PUC.

BACKGROUND: By Order No. 35569, issued on July

12, 2018, the PUC opened the instant docket to

investigate the IGP process. (Docket No. 2018-0165,

Instituting a Proceeding Order No. 30725 To

Investigate Integrated Grid Planning.) Pursuant to

Order No. 35569, the Companies filed their IGP

Workplan on December 14, 2018. The Workplan

described the major steps of the Companies' proposed

IGP process, timelines, and the methods the

Companies intend to employ, including various

Working Groups. On March 14, 2019, the PUC issued

Order No. 36218, which accepted the Workplan and

provided the Companies with guidance on its

implementation.

Based on direction from PUC Order No. 36725,

Providing Guidance on the IGP, HNEI has taken a

leadership role in the IGP’s TAP, which is currently

made up of industry experts from the United States.

Through its November IGP Commission Guidance,

the PUC noted that, “[f]or the stakeholder process

outlined in the Workplan to effectively serve as a

replacement for independent evaluation, the

Technical Advisory Panel would have to take an

active role in analyzing, evaluating, and providing

public feedback on Working Group activities and

Review Point filings.” The PUC continued by stating

its expectation that the Companies “use the Technical


Support of Integrated Grid Planning

Figure 1. IGP process and participants.



Advisory Panel to provide independent review of

each Review Point filing that the Companies will

file.” While noting this more substantive approach,

the TAP is an independent advisory group and is not

a decision-making body, but provides input and

advice on the methods and processes that the

Companies use to perform such work.

PROJECT STATUS/RESULTS: HNEI’s role as the

TAP Chair is an ongoing process that is intended to

continue throughout the IGP process. This includes

regular discussions with the HECO planning team,

meetings with the TAP members, and expanded

engagement in HECO’s technical working groups.

Due to difficulties in ensuring the proper feedback in

developing questions for the TAP to address, the PUC

developed additional requests (and the utility has

accepted and moved on those requests) to have HNEI

play a more substantive role in obtaining additional

outside experts. Further, this PUC directive allows for

HNEI to play a more effective role is assisting HECO

in properly formulating questions and agendas for

TAP meetings.

On May 27, 2020, HECO responded to the PUC in a

lengthy letter that covered a number of topics. One

substantive topic was to acknowledge the expanded

role of HNEI in leading the TAP and assisting the

company in better preparation for meetings. As seen

in Figure 3, there have been delays in meeting the

original timelines. This has been due to a variety of

factors, one of which is the impact of COVID-19.

As a result of these PUC requests, HNEI increased its

interaction with the HECO planning staff to review

the status and direction of the IGP process. As part of

this process, HNEI also helps create consolidated

reporting to better share IGP results with TAP

members who may not be aware of Hawaiʻi-specific

events, trends, or challenges. Finally, HNEI and their

contractor Telos Energy, has become more actively

engaged in other parts of the IGP stakeholder process,

including the Stakeholder Committee and Technical

Working Groups. This allows selected TAP

members, who are also more involved in these

meetings, to have insight and visibility into the

complete stakeholder process, without burdening the

full TAP membership.


Special Fund



Figure 3. Process flow diagram for IGP.




OBJECTIVE AND SIGNIFICANCE: Decarbonizing the

energy sector in Hawaiʻi is a key part of the state’s

energy and environmental objectives. While

significant progress has been achieved in the power

sector, meaningful reduction in the state’s overall

emissions, can only be achieved with significant

greenhouse gas (GHG) emissions reduction from the

transportation sector, which currently accounts for

nearly 60% of the state’s emissions. Electrification of

transportation (EoT), particularly light duty vehicles,

has been identified as a key component to meeting

these goals.

The objective of this work was to quantify the net

GHG benefits of electric vehicles (EV) compared to

the current fleet and other vehicle options. The

analysis, conducted for the island of Oʻahu, included

the impacts of increasing penetration of renewable

energy generation in the power sector and time-of-

day charging of light duty vehicles.

KEY RESULTS: The analysis showed that, while the

transition to EVs for the light duty vehicle fleet does

have the potential to reduce GHG emissions, the

reductions will be quite limited until the renewable

generation on Oʻahu reaches a level requiring

substantial amounts of curtailment. Until then, the

increased demand for electricity to charge vehicles

will require increased oil usage to meet the combined

EV and power sector demand. Based on analysis

conducted by HNEI, significant curtailment on Oʻahu

will not occur until renewable generation is far higher

than it is today (see “Capacity Value of Storage with

High Penetration of PV and Storage” project

summary). In the short term, greater reductions of

GHG can be affected by the replacement of low-

mileage internal combustion engine (ICE) vehicles

with high-mileage energy-efficient hybrid vehicles.

BACKGROUND: As of 2018, there were over 8,400

EVs registered in Hawaiʻi. While this represents only

about one percent of the total passenger vehicle fleet,

their share is growing rapidly increasing by 27%

annually between 2015 and 20181. If these trends

were to continue, there would be over 156,000 EVs

1 DBEDT State of Hawaiʻi Data Book, “Table 18.09-- Vehicle Registration, By Taxation Status” 2 U.S. Energy Information Agency, Energy-Related CO2 Emission Data Tables, “Table 4, 2017 State energy-related carbon dioxide emissions by sector,” https://www.eia.gov/environment/emissions/state/.

by 2030, approximately 20% of today’s total vehicle

fleet.

In light of these trends, the Hawaiʻi Public Utilities

Commission opened Docket No. 2018-0135,

Instituting a Proceeding Related to the Hawaiian

Electric Companies’ Electrification of Transportation

Strategic Roadmap and associated pilot projects. In

2018, the Hawaiʻi state legislature also passed House

Bill 2182, which set a statewide zero emissions clean

economy target, stating that “considering both

atmospheric carbon and greenhouse gas emissions as

well as offsets from the local sequestration of

atmospheric carbon and greenhouse gases through

long-term sinks and reservoirs, a statewide target is

hereby established to sequester more atmospheric

carbon and greenhouse gases than emitted within the

State as quickly as practicable, but no later than

2045.”

PROJECT STATUS/RESULTS: According to the U.S.

Energy Information Agency, Hawaiʻi’s statewide

CO2 emissions were 17.7 MMT in 2017, with

transportation accounting for 58%, electricity

generation accounting for 32%, and the remainder

coming from residential, industrial, and commercial

uses2.

As shown in the figure below, the electric power

sector has reduced emissions by approximately 30%


GHG Reduction from Electrified Transportation



https://www.eia.gov/environment/emissions/state/

https://www.capitol.hawaii.gov/session2018/bills/HB2182_CD1_.htm

https://www.capitol.hawaii.gov/session2018/bills/HB2182_CD1_.htm



since 2008, consistent with the increase in low-

emissions renewable generation. However,

transportation and other sector emissions have

increased slightly during that time. It is important to

note that even if all light duty vehicles are electrified,

approximately 50% of the transportation emissions

result from heavy duty vehicles (7%), marine

transportation (12%), and aviation (28%) remain.

While EVs have zero tailpipe emissions, that does not

mean they are emissions-free. Instead, the indirect

emissions associated with an EV depends on the

emissions rate of the electricity produced to charge

the vehicle. To understand these results, one has to

examine the Hawaiʻi grid compared to that on the

U.S. mainland. Without curtailment of the renewable

generation resources, additional EV charging loads

require increased oil-fired generation to meet the

combined EV-grid demand. This is highly unique to

Hawaiʻi, relative to other North American grids

where charging will be incrementally served by lower

carbon resources, such as natural gas-fired

generation.

While individual homeowners can reduce their

carbon footprint when they have both rooftop PV and

EVs, it does little to change the overall island balance.

Without the EV, their solar energy generation could

have otherwise gone directly to the grid and to offset

oil generation.

To understand the role of electrification of

transportation in reducing GHG emission, grid

models used to evaluate strategies for integration of

renewable generation were modified to include

different levels of EV adoption, up to 40% of the

current light-duty vehicle fleet. This analysis was

conducted for Oʻahu, which accounts for

approximately 70% of the statewide transportation

emissions.

The analysis examined the combined EV-power grid

GHG emissions at both near-term and longer-term

renewable adoption levels. Specifically, the GHG

emissions assumed additional solar + storage

installations ranging from 500 GWh to 3500 GWh

beyond what is currently deployed on Oʻahu,

representing up to 50% of the total Oʻahu generation

mix.

Time-of-day charging is often considered as a means

to manage the use of solar for EV charging. To

explore this issue, HNEI analyzed grid models for

four different charge regimens, shown in the figure

below. While there were modest dependencies on

when the vehicles were charged, the ability of the

utility scale PV + storage to shift energy to when its

needed results in minimal impact.



The system-level results of this analysis, summarized

in the chart at the bottom of the page, show the

combined emissions on Oʻahu from the electric

power sector and light duty vehicle fleet at different

penetrations of solar + storage energy. It assumes

20% of the current light duty vehicles are replaced by

EVs. While electrification of transportation does

decrease the vehicle emissions, it is mostly offset by

an increase in electricity sector emissions from fossil-

fired plants. It is not until Oʻahu reaches very high

levels of PV penetration on the grid that the net

emissions savings start to substantively increase. For

reference, “Capacity Value for Storage” indicates that

with an additional 2000 GWh of solar + storage,

curtailment is only 1-2%, reaching approximately 6%

with 3500 GWH of additional solar + storage energy

generation.

When viewed in the larger context of statewide

emissions, EoT has a marginal effect on total

emissions. The figure to the right shows that with

substantial adoption of renewable energy, a

concurrent drop in GHG emissions will occur within

the state. However, the electrification of light duty

EVs even as high as 40% of the total vehicle fleet, has

minimal additional impact on the reduction of CO2

emissions. For reference, the impact of replacing the

AES coal plant with solar + storage has a significant

impact.

It is not until the grid is more fully decarbonized that

the emissions savings from an EV are higher.

However, as solar generation increases, so does the

underlying emissions benefits. In a high solar grid,

EV charging can be utilized as an effective load

management approach and provide valuable grid

services. This would allow for further PV adoption

and improved emissions benefits.

To date, much of the attention in Hawaiʻi’s energy

policy and planning has been focused on getting the

electric power grid to 100% renewable energy.



Further renewable adoption in the power sector

makes sense as there are commercially available

technologies available today to make that transition

relatively quickly. However, studies suggest that

getting the electric power sector to decarbonize the

last 10-15% of generation will be significantly more

difficult. As a result, if decarbonization of Hawaiʻi’s

energy system is the goal, it may be more effective to

focus on emissions reductions from other sectors,

such as transportation, before advancing to a 100%

renewable grid.








OBJECTIVE AND SIGNIFICANCE: Through this

project, HNEI supports the activities of the Hawaiʻi

Energy Policy Forum (HEPF) in its mission to enable

informed decisions to advance Hawaiʻi’s clean

energy future by convening a network of stakeholders

for fact finding, analysis, information sharing, and

advocacy.

BACKGROUND: The HEPF was established in 2002

as a collaborative energy planning and policy group.

The organization consists of approximately 40

representatives from the electric utilities, oil and

natural gas suppliers, environmental and community

groups, renewable energy industry, academia, and

federal, state, and local government. It is managed by

the University of Hawaiʻi’s College of Social

Sciences. In its early years, the Forum was

instrumental in several significant areas – including

focusing priorities and getting energy issues “on the

decision-making table”, promoting funding and

needed reform for the State’s utility regulatory

agencies (i.e., the Public Utilities Commission (PUC)

and the Division of Consumer Advocacy), and

commissioning studies, reports, and briefings to raise

the level of dialog concerning energy issues for

legislators and the general public. The Forum

sponsors and organizes several well attended annual

events, including Hawaiʻi Clean Energy Day and a

Legislative Briefing at the Capitol at the opening of

each legislative session, and sponsors programs to

develop reliable information and educate and raise

awareness in the community. Two HNEI faculty

members contribute significantly to HEPF activities,

including sitting on the HEPF’s Steering Committee,

chairing the Transportation and Electricity Working

Groups, and hosting and coordinating the weekly

ThinkTech “Hawaiʻi: State of Clean Energy” show.

PROJECT STATUS/RESULTS: During FY 2019-2020,

HEPF focused on developing a list of member-driven

initiatives, encouraging collaborative dialogue by

enhancing the features and usability of the Member

Portal, continuing to develop online resources for

stakeholders and the general public, and organizing a

public briefing. With COVID-19, HEPF is revisiting

and adapting its program accordingly. Specific new

programs include:

Strategic Planning

HEPF held an annual general membership meeting in

October 2019 where members revisited HEPF’s

mission, vision, and values in practice to ensure they

are still serving the Forum well, reported on new

program initiatives, were provided status updates

from various state agencies, discussed next steps for

the Forum, and planned for the upcoming public

briefing.

Member-Driven Initiatives

Peer Exchange Program

In Fall 2019, HEPF held its first round of peer

exchanges (small group policy discussions) on

specific shared energy policy and planning issues

aimed at encouraging collaborative dialogue amongst

members and non-members (including subject matter

experts) to inform policy and action. In the inaugural

round, HEPF sponsored three peer exchange projects

focused on transportation: 1) A Mitigation-

Resilience-Equity Nexus Approach to Clean

Transportation (led by Kauaʻi County); 2) Advancing

and Accelerating Hawaiʻi’s Renewable Energy Goals

through Clean Transportation (led by Hawaiʻi

County); and 3) Benchmarking Low-Carbon

Transportation Policy and Greenhouse Gas Analysis

(led by Simonpietri Enterprises). These peer

exchanges were instrumental in bringing key

stakeholders together (government entities, utilities,

academia, for-profit and not-for-profit sectors, and

included both HEPF and non-HEPF members) and

catalyzing further discussion and action, including

introducing templates for a request for proposal and

contract for electric vehicle procurement in support of

Transportation Services Contracting by State and

County governments.

Due to COVID-19, HEPF has continued its peer

exchange virtually in 2020. In August, HEPF hosted

its first virtual peer exchange event in partnership

with the Department of Land and Natural Resources

(DLNR) to kickstart a project on multi-modal

mobility hubs. The State’s Climate Change

Commission sought and was awarded grant funds

from Oʻahu Metropolitan Planning Organization and

other sources to develop a plan for assessment of state

parking facilities statewide that will allow for multi-

modal use. The HEPF peer exchange program was

aimed at helping determine a general focus for this

project.


Hawaiʻi Energy Policy Forum

https://thinktechhawaii.com/topics/hawaii-state-of-clean-energy/



Online Portal

HEPF revamped its new Member Portal, that serves

as a repository (https://manoa.hawaii.edu/hepf/) for

membership documents and a space to share

information, ask questions, and get feedback. The

relaunch helped accomplish one of the Forum’s goals

to enable greater information sharing and

collaboration. It facilitates greater frequency and

depth of collaboration one-on-one, as well as amongst

a group. The Portal also serves as a springboard for

peer exchanges and other projects. The revamp of the

portal allows for non-members to have access to

certain aspects of the portal to participate in continued

discussion from events such as the peer exchanges.

Public Resources and Events

Annual Briefing

In January 2020, HEPF held an Annual Briefing at the

State Capitol which focused on aligning energy,

transportation, and climate change policy with the

needs of Hawaiʻi residents. The program included

comments from Governor Ige and Representative

Lowen, a keynote presentation from Scott Glenn (the

new CEO of the Hawaiʻi State Energy Office),

discussants from out of state, as well as many

specialized HEPF panelists. The final panel included

a report out of the Fall 2019 peer exchanges.

Online Resources

Between 2019-2020, HEPF developed new resources

and updated existing resources for members and the

public focusing on policy in the legislature and the

PUC. These resources include:

• 2020 State legislature bill tracking spreadsheet,

which documents the progression of bills and

outlines the final scope of bills passed;

• Updated State Act Database to 1999-2020 (from

2002-2018), which includes topic categorization,

and links to the Hawaiʻi Revised Statutes, act

text, and measure history;

• Summary of PUC energy docket proceedings and

key updates;

• Compilation of existing federal policies related to

energy, which includes a description of the policy

(as of June 2020), policy type, relevant sector,

managing agency and federal citations to

amendments; and

• COVID-19 resources website page providing

synthesized COVID-19 related energy

information, which included summaries of

COVID-19 docket proceedings that aim to

mitigate the effects of the crisis including: cost

deferrals, suspending termination/disconnection,

and the fuel supply contract between Hawaiian

Electric Company and Par Hawaiʻi. This

information was also disseminated via a handout

titled ‘What’s changed since COVID-19? A

snapshot of the electricity sector’, which includes

figures using publicly available data to observe

what has happened in the electricity sector since

COVID-19.

Video Series

HEPF is partnered with ThinkTech Hawaiʻi to

produce five energy-related video streaming series

(ranging from weekly to monthly) to inform and

engage the public on energy issues, challenges, and

actions to advance Hawaiʻi’s clean energy future,

available at https://thinktechhawaii.com/. Videos are

livestreamed and available as recordings.

Student Development

Through HEPF, two to three graduate students per

semester and one undergrad web designer have been

funded.


Special Fund

Contact: Richard Rocheleau, [email protected];

Mitch Ewan, [email protected]


https://manoa.hawaii.edu/hepf/

https://thinktechhawaii.com/





OBJECTIVE AND SIGNIFICANCE: Commercial

aviation in Hawaiʻi currently uses nearly 700 million

gallons of jet fuel per year, all of it is derived from

petroleum. The University of Hawaiʻi (UH) is a

member of the Federal Aviation Administration’s

(FAA) Aviation Sustainability Center (ASCENT)

team of U.S. universities conducting research on

production of sustainable aviation fuels (SAF). UH’s

specific objective is to conduct research that supports

development of supply chains for alternative,

renewable, sustainable, jet fuel production in

Hawaiʻi. Results may inform similar efforts in other

tropical regions.

BACKGROUND: This project was initiated in October

2015 and is now continuing into its 6th year.

Activities undertaken in support of SAF supply chain

analysis include:

• Conducting literature review of tropical biomass

feedstocks and data relevant to their behavior in

conversion systems for SAF production;

• Engaging stakeholders to identify and prioritize

general SAF supply chain barriers (e.g. access to

capital, land availability, etc.);

• Developing geographic information system (GIS)

based technical production estimates of SAF in

Hawaiʻi;

• Developing fundamental property data on biomass

resources; and

• Developing and evaluating regional supply chain

scenarios for SAF production in Hawaiʻi.

Figure 1. Commercial and military jet fuel use in 2015;

Total use – 678.4M Gallons.

PROJECT STATUS/RESULTS: Literature reviews of

both biomass feedstocks and their behavior in SAF

conversion processes have been completed and

published. Based on stakeholder input, barriers to

SAF value chain development in Hawaiʻi have been

identified and reported. Technical estimates of land

resources that can support agricultural and forestry-

based production of SAF feedstocks have been

completed using GIS analysis techniques. Samples

from Honolulu’s urban waste streams and candidate

agricultural and forestry feedstocks have been

collected and subjected to physicochemical property

analyses to inform technology selection and design of

SAF production facilities.

Figure 2. Commercial jet fuel consumption in Hawaiʻi.

Fuel Properties of Construction and Demolition

Waste Streams

A sampling and analysis campaign was undertaken to

characterize fuel properties of construction and

demolition waste (CDW) streams on Oʻahu. As

summarized in Figures 3 and 4, although the

combustible fraction of the samples have elevated ash

levels compared to clean biomass materials, their

heating values were comparable, indicating the

presence of higher energy density materials. As with

most refuse derived fuels, the amount of ash in the

fuel and its composition is of particular importance,

since ash impacts energy facility operations,

maintenance, and emissions.

Figure 3. Ash content of the combustible fraction of CDW

compared to construction wood and woody biomass.

0

2

4

6

8

10

12

14

16 CDW

Construction wood

Woody biomass

As

h c

on

ten

t (%

)

Hawaiʻi Natural Energy Institute Research Highlights Alternative Fuels; Energy Efficiency & Transportation

Sustainable Aviation Fuel Production



Figure 4. Heating value of the combustible fraction of

CDW compared to construction wood and woody biomass.

Future work with ASCENT partners includes:

• Analysis of feedstock-conversion pathway

efficiency, product slate (including co-products),

maturation;

• Scoping of techno-economic analysis (TEA) issues;

• Screening level greenhouse gas (GHG) life cycle

assessment (LCA);

• Identification of supply chain participants/partners;

• Continued stakeholder engagement;

• Acquiring transportation network and other

regional data;

• Evaluating infrastructure availability; and

• Evaluating feedstock availability.

Exploration of Biomass Feedstocks for Hawaiʻi

Figure 5 shows the breakdown of land use of the

nearly 2 million acres of agricultural lands in Hawaiʻi.

With the shuttering of much of the cane sugar and the

pineapple industries, this total has dropped further.

Bringing agricultural lands back into production can

support diversification of the economy and support

rural development. Biomass feedstocks for

sustainable aviation fuel production are options that

can contribute to this revitalization. A review of

possible biomass resources and conversion

technologies was performed for Hawaiʻi and the

tropics. This review can be found at

https://dx.doi.org/10.1021/acs.energyfuels.8b03001.

The Eco Crop model was used to complete an

assessment of plant production requirements to agro-

ecological attributes of agricultural lands in the State.

The analysis focused on sites capable of rain fed

production to avoid using irrigated lands that could

support food production. Oil seed crops, woody

crops, and herbaceous crops were all considered; an

example is shown for a eucalyptus species on the

following page (Figure 6). Ongoing work will

identify underutilized agricultural areas and supply

chain components necessary to develop SAF

production systems.

0

5

10

15

20

25

Hig

he

r H

ea

tin

g V

alu

e (

MJ

/kg

)

0

2

4

6

8

10

12

14

16 CDW

Construction wood

Woody biomass

As

h c

on

ten

t (%

)

Figure 5. Breakdown of agricultural land use in Hawaiʻi; in 2015, approximately 100,000 acres were harvested.

https://dx.doi.org/10.1021/acs.energyfuels.8b03001



Figure 6. EcoCrop assessment of Saligna, Eucalyptus.



Evaluation of Pongamia

Of the sustainable aviation fuels currently approved

by ASTM and the FAA, those based on the use of oils

derived from plants and animals have the highest SAF

yield and the lowest production costs. Pongamia

(Milletia pinnata) is a tree, native to the tropics, that

bears an oil seed and has plantings established on

Oʻahu.

Figure 7. Locations and images of Pongamia.

Invasiveness Assessment

Under this project, an observational field assessment

of trees in seven locations on Oʻahu was conducted

by Professor Curtis Daehler (UH Dept. of Botany) to

look for direct evidence of pongamia escaping from

plantings and becoming an invasive weed. Although

some pongamia seedlings were found in the vicinity

of some pongamia plantings, particularly in wetter,

partly shaded environments, almost all observed

seedlings were restricted to areas directly beneath the

canopy of mother trees. This finding suggests a lack

of effective seed dispersal away from pongamia

plantings. Based on its current behavior in the field,

pongamia is not invasive or established outside of

cultivation on Oʻahu. Because of its limited seed

dispersal and low rates of seedling establishment

beyond the canopy, risk of pongamia becoming

invasive can be mitigated through monitoring and

targeted control of any rare escapes in the vicinity of

plantings. Seeds and seed pods are water dispersed,

so future risks of pongamia escape and unwanted

spread would be minimized by avoiding planting at

sites near flowing water, near areas exposed to tides,

or on or near steep slopes. Vegetative spread by root

suckers was not observed around plantings on Oʻahu,

but based on reports from elsewhere, monitoring for

vegetative spread around plantations is

recommended; unwanted vegetative spread might

become a concern in the future that could be

addressed with localized mechanical or chemical

control.

Fuel properties

Pongamia is a potential resource for renewable fuels

in general and sustainable aviation fuel in particular.

This project characterized physicochemical

properties of reproductive material (seeds and pods)

from pongamia trees grown in different environments

at five locations on Oʻahu. Proximate and ultimate

analyses, heating value, and elemental composition of

the seeds, pods, and de-oiled seed cake were

determined. The oil content of the seeds and the

properties of the oil were determined using American

Society for Testing and Materials (ASTM) and

American Oil Chemist’s Society (AOCS) methods.

The seed oil content ranged from 19 to 33 % wt.

across the trees and locations. Oleic (C18:1) was the

fatty acid present in greatest abundance (47 to 60 %

wt) and unsaturated fatty acids accounted for 77 to 83

% wt of the oil. Pongamia oil was found to have

similar characteristics as other plant seed oils (canola

and jatropha) and would be expected to be well suited

for hydro-processed production of sustainable

aviation fuel.

Figure 8. Pathways from Pongamia seed pods to fuel.

Coproduct Development

Additional study was devoted to developing

coproducts from pongamia pods. Torrefaction is a

thermochemical treatment method conducted at



200-300°C and atmospheric pressure in the absence

of oxygen. The main objective is to reduce the oxygen

content of the torrefied product compared to the

parent biomass. In general, torrefaction of woody

biomass materials results in mass and energy yields

of 70 % and 90 %, respectively. Consequently, energy

densification (mass basis) improvement by a factor of

1.3 is typical. The mass fraction of the parent biomass

volatilized during torrefaction (~30%) is of low

energy content, only ~10% of the total energy.

Torrefied materials generally possess higher energy

density, better grindability, better hydrophobicity and

biological stability, which can all contribute to

reducing the overall conversion cost. In addition, the

torrefied biomass should have lower H/C and O/C

ratio compared to the raw biomass.

Figure 9. Laboratory scale torrefaction test bed.

Figure 10. Torrefied pongamia pods prepared at varied

treatment temperatures.

Funding Source: Federal Aviation Administration;

Energy Systems Development Special Fund

Contact: Scott Turn, [email protected]





OBJECTIVE AND SIGNIFICANCE: The purpose of this

project was to develop a biorefinery technology to

produce biochar-like solid fuel and bioplastics from

cellulosic biomass. The bioplastics have a much

higher monetary value than solid fuel and hence

reduce the cost of solid fuel for power generation. The

carbon-neutral solid fuel can supplement the

intermittent solar and wind powers.

BACKGROUND: Cellulosic biomass from agriculture

and forest management is an under-utilized

renewable resource. The major compoents of raw

biomass are cellulsoe (30-50% wt), hemicellulsoe

(15-25% wt) and lignin (20-35% wt). Compared to

lignite coal (~$20/ton), raw biomass is expensive

(~$60/ton) and has a relatively low heating value

(HHV 17-19 MJ/kg) because of the high atomic O/C

ratio of cellulose and hemicellulose. However,

cellulose and hemicellulose could be a potential

feedstock for high value products such as bioplastics.

PROJECT STATUS/RESULTS: The research

investigated chemical and biological conversions of

woody biomass. Under thermal catalytic hydrolysis

conditions, sawdust was converted into hydrochar, a

biochar like solid as shown in Figure 1. The cellulose

and hemicellulose in raw biomass were completely

converted into organic acids, primarily levulinic and

formic acids. Accounting for ~45% wt of raw

biomass, the hydrochar has a heating value of lignite

coal (HHV 25 MJ/kg), which is higher than the

heating values of raw or torrefied biomass. Since the

cellulose, hemicellulose, organic extractives, and

minerals have been removed, the hydrochar has a

lower atomic O/C ratio and is cleaner than raw

biomass. The lignite-grade hydrochar performs better

than raw biomass for power generation. In addition to

the major organic acids, the hydrolysates solution

contained minor byproducts including furfurals and

phenolic compounds that were inhibitive to microbes.

The research measured the microbial yields on

individual hydrolysates and determined the inhibitive

concentration levels for detoxification operation and

fermentation control. After proprietary treatment, the

biomass hydrolysates could be utilized by microbes

to form polyhydroxyalkanoate (PHA). The PHA

bioplastics exhibit the material properties of

conventional plastics such as polypropylene and can

be completely degraded into water and carbon

dioxide by microorganisms in the environment,

including marine waters.

According to the experimental results, 100 lbs of raw

woody biomass (dry base) can be converted into ~45

lbs of hydrochar (~$0.03/lb) and ~10 lbs of

bioplastics (~$2/lb). The technology can increase the

value of raw biomass by more than four folds. As a

result, the hydrochar could be used as a carbon neutral

solid fuel for power generation at a competitive price

of lignite-grade coal.

The project has generated four technical reports, four

research articles in peer-reviewed scientific journals,

and two presentations in national and international

conferences.

Funding Source: Bio-on S. p.A.

Contact: Jian Yu, [email protected]

Last Updated: October 2020

Hawaiʻi Natural Energy Institute Research Highlights Alternative Fuels

PHA Bioplastics from Biomass

Figure 1. Conversion of wood sawdust into hydrochar and bioplastics.




ADDITIONAL PROJECT RELATED LINKS

BOOK CHAPTERS:

1. 2013, J. Yu, Production of Polyhydroxyalkanoates in Biomass Refining, in S-T. Yang, H. El-Ensashy,

N. Thongchul (eds.) Bioprocessing Technologies in Biorefinery for Sustainable Production of Fuels,

Chemicals, and Polymers, John Wiley & Sons, Inc., Chapter 22, pp. 415-426.

2. 2010, J. Yu, Biosynthesis of Polyhydroxyalkanoates from 4-Ketovaleric Acid in Bacterial Cells, in

H.N. Cheng, R.A. Gross (eds.) Green Polymer Chemistry: Biocatalysis and Biomaterials, American

Chemical Society, Chapter 12, pp. 161-173.

3. 2009, J. Yu, Production of green bioplastics from agri-food chain residues and co-products, in K.

Waldron (ed.), Handbook of Waste Management and Co-Product Recovery in Food Processing, Vol. 2,

Woodhead Publishing Limited, Chapter 21, pp. 515-536.

4. 2006, J. Yu, Microbial Production of Bioplastics from Renewable Resources, in S-T. Yang (ed.),

Bioprocessing for Value-Added Products from Renewable Resources, Elsevier, Chapter 23, pp 585-610.

PAPERS AND PROCEEDINGS:

1. 2020, P-C. Kuo, J. Yu, Process simulation and techno-economic analysis for production of

industrial sugars from lignocellulosic biomass, Industrial Crops and Products, Vol. 155, Paper 112783.

2. 2016, S. Kang, J. Yu, An intensified reaction technology for high levulinic acid concentration from

lignocellulosic biomass, Biomass and Bioenergy, Vol. 95, pp. 214-220.

3. 2015, S. Kang, J. Yu, Effect of Methanol on Formation of Levulinates from Cellulosic Biomass,

Industrial & Engineering Chemistry Research, Vol. 54, Issue 46, pp. 11552-11559.

4. 2014, N. Tanadchangsaeng, J. Yu, Thermal stability and degradation of biological terpolyesters over

a broad temperature range, Journal of Applied Polymer Science, Vol. 132, Issue 13, pp. 41715-41815.

5. 2014, P. Tang, J. Yu, Kinetic analysis on deactivation of a solid Brønsted acid catalyst in conversion

of sucrose to levulinic acid, Indus. & Engin. Chemistry Research, Vol. 53, Issue 29, pp. 11629-11637.

6. 2013, N. Tanadchangsaeng, J. Yu, Miscibility of natural polyhydroxyalkanoate blend with

controllable material properties, Journal of Applied Polymer Science, Vol. 129, Issue 4, pp. 2004-2016.

7. 2011, M. Jaremko, J. Yu, The initial metabolic conversion of levulinic acid in Cupriavidus

necator, Journal of Biotechnology, Vol. 155, Issue 3, pp. 293-298.

8. 2008, J. Yu, L.X.L. Chen, The Greenhouse Gas Emissions and Fossil Energy Requirement of

Bioplastics from Cradle to Gate of a Biomass Refinery, Environmental Science & Technology, Vol.

42, Issue 18, pp. 6961-6966.

9. 2008, J. Yu, H. Stahl, Microbial utilization and biopolyester synthesis of bagasse hydrolysates,

Bioresource Technology, Vol. 99, Issue 17, pp. 8042-8048.

PRESENTATIONS:

1. 2020, J. Yu, Ductile Bioplastics and Lignite-grade Fuel from Cellulosic Biomass, Presented at the

European Biomass Conference & Exhibition, Marseille, France, April 27-30.

2. 2016, J. Yu, A Two-stage Process to Produce Ductile Bioplastics from Cellulosic Biomass, Presented

at the World Congress on Industrial Biotechnology, San Diego, California, April 17-20.

STUDENT THESES:

1. 2011, M.J. Jaremko, Polyhydroxyalkanoate synthesis by ralstonia eutropha from multiple

substrates, Master of Science Thesis, Department of Molecular Bioscience and Bioengineering,

University of Hawaiʻi at Mānoa, Honolulu, HI.

LABORATORY: BIOPROCESSING LAB

http://dx.doi.org/10.1002/9781118642047.ch22

http://dx.doi.org/10.1002/9781118642047

http://dx.doi.org/10.1002/9781118642047

https://dx.doi.org/10.1021/bk-2010-1043.ch012

https://dx.doi.org/10.1021/bk-2010-1043

https://dx.doi.org/10.1533/9781845697051.4.515

https://dx.doi.org/10.1533/9781845697051

https://dx.doi.org/10.1016/B978-044452114-9/50024-4

https://dx.doi.org/10.1016/B978-0-444-52114-9.X5000-2

http://dx.doi.org/10.1016/j.indcrop.2020.112783

http://dx.doi.org/10.1016/j.indcrop.2020.112783

http://dx.doi.org/10.1016/j.biombioe.2016.10.009

http://dx.doi.org/10.1016/j.biombioe.2016.10.009

http://dx.doi.org/10.1021/acs.iecr.5b03512

http://dx.doi.org/10.1002/app.41715


http://dx.doi.org/10.1021/ie501044c

http://dx.doi.org/10.1021/ie501044c



http://dx.doi.org/10.1016/j.jbiotec.2011.07.027

http://dx.doi.org/10.1016/j.jbiotec.2011.07.027

http://dx.doi.org/10.1021/es7032235

http://dx.doi.org/10.1021/es7032235

http://dx.doi.org/10.1016/j.biortech.2008.03.071

http://www.hnei.hawaii.edu/wp-content/uploads/2020-EBCE_Ductile-Bioplastics-and-Fuel-from-Biomass.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/2016-WCIB_Two-stage-Process-to-Produce-Bioplastics.pdf

http://hdl.handle.net/10125/101705


http://www.hnei.hawaii.edu/facilities/bioprocessing-lab/




this project is to identify and characterize trace

quantities of heteroatomic organic species (HOS) in

aviation, maritime, and diesel fuels. New analytical

methods under development can evaluate the

composition of fuels currently in use and those stored

as strategic reserves. The knowledge gained in this

project will improve the understanding of the

influences of HOS on fuel stability and guide efforts

to preserve fuel quality.

BACKGROUND: Liquid fuels are, by nature,

chemically complex. Many fit-for-purpose and

stability issues are associated with trace quantities of

HOS. Identification and quantitation of HOS are

challenging due to their low concentration and

complex composition of fuel matrix.

Multidimensional gas chromatography (MDGC)

typically uses sequential separations based on

differences in polarity and boiling point as the basis

for fuel sample analysis. The current state-of-the-art

for MDGC is comprehensive two-dimensional GC

(2D-GC).

HNEI began developing a fuel laboratory in 2012 and

the current capabilities include standard analysis

methods required by ASTM and military fuel

specifications. Research conducted in the fuel

laboratory has included investigating the impacts of

long-term storage, oxidative conditions,

contaminants, etc. of conventional and alternative

fuels and their blends.

A 2D-GC was acquired in August 2018, expanding

the fuel laboratory’s ability to identify and quantify

fuel constituents present in trace amounts (≤100

ppm). The HNEI 2D-GC employs two injectors and

three detectors (i.e. mass spectrometer, nitrogen

chemiluminescence and sulfur chemiluminescence)

to analyze fuel components and HOS with a single

injection event. Neat fuels can be injected directly

without requiring solvent dilution.

PROJECT STATUS/RESULTS: HNEI is currently

collaborating with personnel from the U.S. Navy

Fuels Cross-Functional Team on 2D-GC

applications, including:

• Determining fuel hydrocarbon matrix;

• Investigating the distribution and contents of

nitrogen and sulfur compounds in fuels;

• Participating in round robin tests to identify and

quantify nitrogen compounds in various type of

fuels;

• Exploring the relationships between fuel long-

term storage and the content of antioxidant

additives; and

• Utilizing HOS characterization methods to

investigate the potential impacts of HOS on fuel

properties and fuel stability.

Funding Source: Office of Naval Research

Contact: Scott Turn, [email protected]; Jinxia Fu,

[email protected]



Fuel Characterization by Multidimensional Gas Chromatography





OBJECTIVE AND SIGNIFICANCE: To produce a

master design, inclusive of PID diagrams, costing,

manufacturing, and shipping to build and install a

wastewater treatment system designed from past

research and commercial demonstration projects. Its

importance lies in its commercial scale modular-

based designed. The system fits niche opportunities

where concentrated wastewater streams need to be

treated on-site prior to discharge to pre-existing

wastewater lines. The modular nature allows non-

concrete permanent installations that can be tailored

to specific wastewater flows and concentration of

pollutants.

BACKGROUND: Over a number of years, an up-flow

anaerobic packed bed reactor was developed. Packed

with biochar in various formulations, these reactors

were verified at lab and demonstration scale to treat

high and low strength wastewaters efficiently. These

exercises served to verify lab generated results upon

scale up to commercial size and to provide crucial

insights for design revision, as well as experience for

discussion with manufacturers as well as equipment

selection.

From this work, PID diagrams have been constructed

that have considered targeted organic loading rates

and hydraulic retention times. These designs are

accounting for modular fabrication of reactor units,

dimensions of reactors and pipes, piping size, recycle

lines, details of how to install and connect modules,

utilities and electrical, materials of construction,

sources of manufacturing, packing materials,

shipping and installation issues, among others.

Finally, cost estimates for fabrication, shipping, and

installation were estimated and three-dimensional

renderings were generated.

PROJECT STATUS/RESULTS: This project has

produced a number of works that can be found on the

following page. The PI is seeking industrial partners

to apply the system. The PI is also extending the

modeling efforts to execute a cost-benefit analyses

comparing WWTPs producing potable water versus

reusable non-potable water. Key metrics of success

are both energy use and GHG emission per unit

volume water produced. Outcomes will help

determine the relative choice of producing non-

potable versus potable water.


Contact: Michael Cooney, [email protected]



High Rate Anaerobic-Aerobic Digestion





TECHNICAL REPORTS:

1. 2014, M.J. Cooney, Anaerobic Digestion of Primary Sewage Effluent, Report produced for

the Hawaiʻi Energy Sustainability Program (HESP), under U.S. Department of Energy Grant

Award DE-EE0003507.


1. 2020, S. Lin, K. Rong, K.M. Lamichhane, R.W. Babcock, M. Kirs, M.J. Cooney, Anaerobic-

aerobic biofilm-based digestion of chemical contaminants of emerging concern (CEC) and

pathogen indicator organisms in synthetic wastewater, Bioresource Technology, Vol. 299,

Paper 122554.

2. 2019, M.J. Cooney, K. Rong, K.M. Lamichhane, Cross comparative analysis of liquid phase

anaerobic digestion, Journal of Water Process Engineering, Vol. 29, Article 100765.

3. 2017, K.M. Lamichhane, K. Lewis, K. Rong, R.W. Babcock Jr., M.J. Cooney, Treatment of

high strength acidic wastewater using passive pH control, Journal of Water Process

Engineering, Vol. 18, pp. 198-201.

4. 2017, K.M. Lamichhane, D. Furukawa, M.J. Cooney, Co-Digestion of Glycerol with Municipal

Wastewater, Chemical Engineering & Process Techniques, Vol. 3, Issue 1, Paper 1034.

5. 2016, M.J. Cooney, K. Lewis, K. Harris, Q. Zhang, T. Yan, Start up performance of biochar

packed bed anaerobic digesters, Journal of Water Process Engineering, Vol. 9, pp. e7-e13.

6. 2014, R.J. Lopez, S.R. Higgins, E. Pagaling, T. Yan, M.J. Cooney, High rate anaerobic

digestion of wastewater separated from grease trap waste, Renewable Energy, Vol. 62,

pp. 234-242.

PRESENTATIONS:

1. 2014, M.J. Cooney, Low Energy High Rate Anaerobic – Aerobic Digestion (HRAAD) and

Applications, Presented at the ECS MA2014-02 Meeting, Cancun, Mexico, October 5-9,

Abstract 2288.

http://www.hnei.hawaii.edu/wp-content/uploads/Anaerobic-Digestion-of-Primary-Sewage-Effluent.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/HESP-Final-Technical-Report.pdf

https://dx.doi.org/10.1016/j.biortech.2019.122554



https://dx.doi.org/10.1016/j.jwpe.2019.02.005

https://dx.doi.org/10.1016/j.jwpe.2019.02.005

http://dx.doi.org/10.1016/j.jwpe.2017.06.014


https://pdfs.semanticscholar.org/c34f/d854b32cc505791926b263c768519287c7c0.pdf?_ga=2.29675641.777363581.1583369656-1003766740.1583369656

https://pdfs.semanticscholar.org/c34f/d854b32cc505791926b263c768519287c7c0.pdf?_ga=2.29675641.777363581.1583369656-1003766740.1583369656



http://dx.doi.org/10.1016/j.renene.2013.06.047

http://dx.doi.org/10.1016/j.renene.2013.06.047

https://dx.doi.org/10.1149/MA2014-02/50/2288

https://dx.doi.org/10.1149/MA2014-02/50/2288



OBJECTIVE AND SIGNIFICANCE: The purpose of this

project was to develop technologies to produce high-

grade liquid fuel from synthesis gas derived from

agricultural wastes. The drop-in liquid fuel can be

directly used in modern engines of vehicles and ships

without sacrifice of engine performance.

BACKGROUND: Agricultural wastes are underutilized

renewable resource with low heating values (HHV

15-18 MJ/kg) and high oxygen contents (40-50 wt%).

The composition of raw biomass varies depending on

plant species and farming conditions. It is a technical

challenge to convert agriculture wastes into high-

grade liquid fuels that meet the fuel standards of

modern engines. The biomass wastes, however, can

be gasified into a synthesis gas (syngas) that contains

primarily carbon monoxide (CO), hydrogen (H2) and

carbon dioxide (CO2). The new technologies in

development produce polyhydroxybutyrate (PHB)

from the syngas by using microbial organisms and

then reform the PHB polyester into gasoline-grade

liquid fuel.

PROJECT STATUS/RESULTS: Two core technologies

were investigated and developed: (a) microbial gas

fermentation and (b) thermal catalytic reforming of

PHB. Because of the poor solubility of gas in aqueous

solution, a novel bioreactor was invented to enhance

the mass transfer of gas substrates in aqueous solution

by 40-200% in comparison with conventional aerated

bioreactors. In addition, a continuous liquid flow

operation mode of the bioreactor further increased the

productivity up to 2 g/L.h, the benchmark of fuel

ethanol fermentation. Under controlled conditions,

the microbial cells formed a large amount of PHB

(60% of cell mass) as an energy storage material. The

novel bioreactor was scaled up to 200 liters for a pilot

project that is in negotiation with potential industrial

partners and investors.

PHB was recovered and reformed on a solid acid

catalyst under mild conditions (<240 oC) to form a

hydrocarbon oil. The major compounds of the PHB

oil were alkanes, alkenes, and aromatics, the same

compounds found in fossil gasoline and diesel.

Depending on boiling points, the PHB oil was divided

into a light oil (77 wt%) and a heavy oil (23 wt%).

Their elemental compositions and heating values

were determined and compared with commercial

gasoline and biodiesel as shown in Table 1. The light

oil has the same elemental composition and heating

value of the gasoline obtained from a local gas station

and the heavy oil is very close to a commercial

biodiesel.

PHB is a polyester of 3-hydroxybutyrate (C4H5O2)

and contains a substantial amount of oxygen (38%

wt). Oxygen removal is essential to make

hydrocarbon compounds for high heating value and

desired fuel performance. The research identified the

main reactions and key intermediates in the catalytic

reforming of PHB. It was revealed that oxygen was

removed as CO2 without hydrogen consumption, a

techno-economic advantage in comparing with other

biofuel technologies that consume large amounts of

hydrogen.

The project, now completed, has generated four

reports and twelve research articles in peer-reviewed

scientific journals. One invention of novel bioreactor

has been disclosed and filed for global patents.


Contact: Jian Yu, [email protected]



Liquid Fuels from Synthesis Gas

Table 1. Comparison of PHB oils with commercial gasoline and biodiesel

Liquid Fuels Gasoline Light PHB oil Heavy PHB oil Biodiesel

Boiling Points (oC) 40-200 40-240 240-310 180-330

C (wt %) 80.4 81.4 79.4 77

H (wt %) 12.3 11.3 9.7 11.8

N (wt %) 0.1 0.1 0.2 -

O (wt %) 7.2 7.2 10.7 11.2

Heating Value (HHV MJ/kg) 41.8 41.4 38.4 39.7





TECHNICAL REPORTS:

1. 2019, J. Yu, Liquid Fuels from Syngas, Task 3.3, in APRISES 14 Final Technical Report,

Office of Naval Research Grant Award Number N00014-15-1-0028.

2. 2018, J. Yu, Liquid Fuels from Synthesis Gas, Task 3.2d, in APRISES 12 Final Technical

Report, Office of Naval Research Grant Award Number N00014-13-1-0463.

3. 2018, J. Yu, Liquid fuels from Synthesis Gas, Task 3.2d, in APRISES 13 Final Technical

Report, Office of Naval Research Grant Award Number N00014-14-1-0054.

4. 2017, J. Yu, Biochemical Conversion of Synthesis Gas into Liquid Fuels, Task 3.2d, in

APRISES 11 Final Technical Report, Office of Naval Research Grant Award Number N00014-

12-1-0496.


1. 2019, J. Yu, Y. Lu, Carbon dioxide fixation by a hydrogen-oxidizing bacterium: Biomass

yield, reversal respiratory quotient, stoichiometric equations and bioenergetics,

Biochemical Engineering Journal, Vol. 152, Article 107369.

2. 2018, J. Yu, P. Munasinghe, Gas Fermentation Enhancement for Chemolithotrophic Growth

of Cupriavidus necator on Carbon Dioxide, Fermentation, Vol. 4, Issue 3, Paper 63. (Open

Access: PDF)

3. 2018, J. Yu, Fixation of carbon dioxide by a hydrogen-oxidizing bacterium for value-added

products, World Journal of Microbiology and Biotechnology, Vol. 34, Issue 7, Article 89.

4. 2017, Y. Lu, J. Yu, Comparison analysis on the energy efficiencies and biomass yields in

microbial CO2 fixation, Process Biochemistry, Vol. 62, pp. 151-160.

5. 2017, Y. Lu, J. Yu, Gas mass transfer with microbial CO2 fixation and poly(3-

hydroxybutyrate) synthesis in a packed bed bioreactor, Biochemical Engineering Journal,

Vol. 122, pp. 13-21.

6. 2015, S. Kang, J. Yu, A gasoline-grade biofuel formed from renewable polyhydroxybutyrate

on solid phosphoric acid, Fuel, Vol. 160, pp. 282-290.

7. 2015, S. Kang, J. Yu, Reaction routes in catalytic reforming of poly(3-hydroxybutyrate) into

renewable hydrocarbon oil, RSC Advances, Vol. 5, Issue 38, pp. 30005-30013.

8. 2014, S. Kang, J. Yu, One-pot production of hydrocarbon oil from poly(3-

hydroxybutyrate), RSC Advances, Vol. 4, Issue 28, pp. 14320-14327.

9. 2013, J. Yu, A. Dow, S. Pingali, The energy efficiency of carbon dioxide fixation by a

hydrogen-oxidizing bacterium, International Journal of Hydrogen Energy, Vol. 38, Issue 21,

pp. 8683-8690.

10. 2011, M.M. Porter, J. Yu, Crystallization kinetics of poly(3-hdyroxybutyrate) granules in

different environmental conditions, Journal of Biomaterials and Nanobiotechnology, Vol.

2011, Issue 2, pp. 301-310. (Open Access: PDF)

11. 2011, M. Porter, J. Yu, Monitoring in situ crystallization of biopolyester granules in

Ralstonia eutropha via infrared spectroscopy, Journal of Microbiological Methods, Vol. 87,

Issue 1, pp. 49-55.

12. 2008, Z. Xu, J. Yu, Hydrodynamics and mass transfer in a novel multi-airlifting bioreactor,

Chemical Engineering Science, Vol. 63, Issue 7, pp. 1941-1949.

http://www.hnei.hawaii.edu/wp-content/uploads/APRISES-14-Final-Technical-Report.pdf#page=45

http://www.hnei.hawaii.edu/wp-content/uploads/APRISES-14-Final-Technical-Report.pdf









http://dx.doi.org/10.1016/j.bej.2019.107369

http://dx.doi.org/10.1016/j.bej.2019.107369

http://dx.doi.org/10.3390/fermentation4030063

http://dx.doi.org/10.3390/fermentation4030063

https://www.mdpi.com/2311-5637/4/3/63/pdf

https://dx.doi.org/10.1007/s11274-018-2473-0

https://dx.doi.org/10.1007/s11274-018-2473-0

http://dx.doi.org/10.1016/j.procbio.2017.07.007

http://dx.doi.org/10.1016/j.procbio.2017.07.007

http://dx.doi.org/10.1016/j.bej.2017.02.013

http://dx.doi.org/10.1016/j.bej.2017.02.013

http://dx.doi.org/10.1016/j.fuel.2015.07.107

http://dx.doi.org/10.1016/j.fuel.2015.07.107

http://dx.doi.org/10.1039/C5RA03195H




http://dx.doi.org/10.1016/j.ijhydene.2013.04.153


http://dx.doi.org/10.4236/jbnb.2011.23037

http://dx.doi.org/10.4236/jbnb.2011.23037

http://www.scirp.org/pdf/JBNB20110300010_68029463.pdf

http://dx.doi.org/10.1016/j.mimet.2011.07.009

http://dx.doi.org/10.1016/j.mimet.2011.07.009

http://dx.doi.org/10.1016/j.ces.2007.12.026



PRESENTATIONS:

1. 2019, J. Yu, Drop-in Transportation Fuels from Renewable Hydrogen and Carbon Dioxide,

Presented at the Would Hydrogen Technologies Convention, Tokyo, Japan, June 2-7.

2. 2018, J. Yu, A Green Plastic and Drop-in Transportation Fuels from Carbon Dioxide and

Renewable Energy, Proceeding of the TechConnect World Innovation Conference & Expo,

TechConnect Briefs, Vol. 2 Materials for Energy, Efficiency and Sustainability: TechConnect

Briefs, pp. 187-190.

3. 2017, J. Yu, Drop-in Transportation Fuels from Carbon Dioxide and Solar Hydrogen,

Presented at the Environmental and Energy Resource Management Summit, Washington, DC,

November 9-11.

4. 2015, J. Yu, Direct Production of Bioplastics and Chemicals from Carbon Dioxide and

Solar Energy, Presented at the European Meeting on Chemical Industry and Environment,

Tarragona, Spain, June 10-12.

5. 2014, P. Munasinghe, S. Kang, J. Yu, Renewable Hydrocarbon Oils and Chemicals from

Solar Energy and Carbon Dioxide, Presented at the Asia Pacific Clean Energy Summit and

Expo, Honolulu, Hawaii, September 15-17.

6. 2013, J. Yu, Direct Conversion of CO2 into Biopolyester with Solar Energy and Water,

Presented at the American Chemical Society National Meeting, Indianapolis, Indiana September

8-12.

7. 2012, J. Yu, Clean Production of Bioplastics and Bio-Oil from Solar Energy and Carbon

Dioxide, Presented at the CleanTech Conference & Showcase, Santa Clara, California, June 18-

21, 2012.

STUDENT THESES:

1. 2012, A.R. Dow, Novel method for determination of gas consumption in Cupriavidus

necator : assessing feasibility of CO2 fixation from biomass-derived syngas, Master of

Science Thesis, Department of Molecular Bioscience & Bioengineering, University of Hawaii at

Manoa, Honolulu, HI.

2. 2010, M.M. Porter, In situ crystallization of native poly(3-hydroxybutyrate) granules in

varying environmental conditions, Master of Science Thesis, Department of Bioengineering,

University of Hawaii at Manoa, Honolulu, HI.

3. 2007, Z. Xu, Hydrodynamics and mass transfer in a novel multi-airlifting membrane

bioreactor, Master of Science Thesis, Department of Bioengineering, University of Hawaii at

Manoa, Honolulu, HI.

LABORATORY: BIOPROCESSING LAB

http://www.hnei.hawaii.edu/wp-content/uploads/2019-WHTC_Drop-in-Transportation-Fuels-from-Renewable-Hydrogen-and-Carbon-Dioxide.pdf

https://briefs.techconnect.org/papers/a-green-plastic-and-drop-in-transportation-fuels-from-carbon-dioxide-and-renewable-energy/

https://briefs.techconnect.org/papers/a-green-plastic-and-drop-in-transportation-fuels-from-carbon-dioxide-and-renewable-energy/

http://www.hnei.hawaii.edu/wp-content/uploads/2017-EERMS_Drop-in-Transportation-Fuels-from-Carbon-Dioxide-and-Solar-Hydrogen.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/2015-EMCIE_Direct-Production-of-Bioplastics.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/2015-EMCIE_Direct-Production-of-Bioplastics.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/2014-APCES-Renewable-Hydrocarbon-Oils.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/2014-APCES-Renewable-Hydrocarbon-Oils.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/2013-ACS-CO2-Into-Biopolyester.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/2012-CleanTech-Bioplastic-and-Bio-Oil-Clean-Production.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/2012-CleanTech-Bioplastic-and-Bio-Oil-Clean-Production.pdf







http://www.hnei.hawaii.edu/facilities/bioprocessing-lab/



OBJECTIVE AND SIGNIFICANCE: HNEI has installed

a 65kg/day hydrogen production and dispensing

station on the Island of Hawaiʻi at the Natural Energy

Laboratory Hawaiʻi Authority (NELHA) (Figure 1).

The objective of the project is to evaluate the

technical and financial performance, and durability of

the equipment, and support a fleet of three hydrogen

Fuel Cell Electric Buses (FCEB) operated by the

County of Hawaiʻi Mass Transit Agency (MTA). The

knowledge gained in this project will inform the

MTA on benefits and issues associated with

transitioning from a diesel bus fleet to a zero

emissions FCEB fleet in support of the State of

Hawaiʻi’s clean transportation goals. The knowledge

will also be transferred to other counties to assist them

in evaluating the deployment of zero emission buses

for their public transportation fleets.

Figure 1: Hawaiʻi Hydrogen Station.

BACKGROUND: Development of hydrogen-based

transportation systems requires hydrogen

infrastructure to produce, compress, store, and deliver

the hydrogen, a means to dispense the fuel, and

vehicles capable of using high purity hydrogen. The

HNEI hydrogen station at NELHA has been designed

to dispense hydrogen at 350 bar (5,000 psi). Rather

than use ground mounted permanent tank storage,

HNEI will demonstrate centralized hydrogen

production and distributed dispensing with a fleet of

three hydrogen transport trailers (HTT). High purity

hydrogen produced at the NELHA site will be

delivered to the MTA base yard in Hilo to support

deployment of heavy-duty FCEBs operated by the

MTA Hele-On public bus service. The concept is

illustrated in Figure 2.

In additon to the technical and cost analysis, HNEI is

developing implementation plans to support the

introduction of zero emission transportation systems.

HNEI is coordinating with the University of

Hawaiʻi’s Hawaiʻi Community College supporting

the introduction of workforce development programs

to train technicians to service the FCEBs and other

battery electric vehicles.

Figure 2: Hydrogen Transport Concept.


Hydrogen Station

Figure 3: HNEI Hydrogen Station.

The site works as well as the hydrogen production and

compression systems equipment have been installed

at NELHA (Figure 3). The station is in the final stages

of being commissioned by HNEI and Powertech, the

equipment supplier. The station uses a Proton Onsite

(now Nel) electrolyzer to produce 65 kg of hydrogen

per day at an outlet pressure of 30 bar (440) psi. A

HydroPak compressor (Figure 4) compresses the

hydrogen to 450 bar (6,600 psi).

Figure 4: HydroPac Compressor.

Hawaiʻi Natural Energy Institute Research Highlights Alternative Fuels; Electrochemical Power Systems

NELHA Hydrogen Station and Fuel Cell Electric Buses



The system is powered by the HELCO grid which

includes a substantial fraction of renewable energy

including solar, wind, and geothermal.

Hydrogen Transport Trailers

Three trailers (Figure 5) are available for transport

between the production and fueling site. The trailers

were recently hydrostatically tested, pressure and

thermal relief safety valves were upgraded, and the

trailers were recertified by the Federal Transit

Administration for use on U.S. public roads. The

hydrogen cylinders must be recertified every five

years.

Figure 5: Hydrogen Transport Trailers.

Hydrogen Dispensing System

The dispensing system consists of a dispenser (Figure

6) connected to a fueling trailer through a fueling post

interface (Figure 7) that is connected to the dispenser

via an underground hydrogen piping distribution

system. The hydrogen dispenser is fully automated

and programmed to “fail safe” for unattended

operation.

Figure 6: Hydrogen Dispenser.

Figure 7: NELHA Fueling Post Interface.

The fueling dispensers located at NELHA and at

MTA are identical except for the addition of a boost

compressor at the MTA site integrated into the MTA

fueling post (Figure 8). The boost compressor system

was developed by HNEI and Powertech to dispense

up to 90% of the hydrogen stored in the HTT in order

to reduce transportation costs by not having to return

half-filled trailers to be refilled at NELHA.

Figure 8: MTA Boost Compressor Fueling Post.

Hele-On 29-Passenger Fuel Cell Electric Bus

The Hele-On 29-passenger FCEB (Figure 9) was

purchased with funds from the Energy Systems

Development Special Fund. This bus, manufactured

by Eldorado National and converted to a hydrogen-

electric drive train by U.S. Hybrid is ADA-compliant.

The fuel cell power system was recently upgraded by

replacing the original 30 kW Hydrogenics fuel cell

with a new state-of-the-art 40 kW U.S. Hybrid fuel

cell.



Figure 9: Hele-On 29-Passenger FCEB.

Onboard hydrogen is stored in composite carbon

fiber cylinders located under the bus with a capacity

of 20kg. The fuel cell power system is integrated with

two 11 kWh A123 Lithium-ion battery packs to

provide motive power to a 200 kW electric drive

system. U.S. Hybrid also replaced batteries with the

new technology A123 batteries using U.S. Hybrid

internal funding. At cruising speed, the fuel cell

maintains the battery state of charge within a range

that supports the long-term health of the battery.

During deceleration, the electric motor acts as a

generator sending power back into the battery

(“regenerative braking”). This contributes to overall

system energy efficiency and improves bus mileage.

The bus has a range of approximately 200 miles

depending on the route topography and driver skills.

Bus Export Power Unit

A 10 kW export power system (Figure 10) was

installed in the 29-passenger bus to enable the bus to

provide 110/220VAC electric power at full power for

up to 30 hours as emergency power for civil defense

resilience operations when the grid power is down.

The bus can be refueled in 10 minutes providing an

additional 30 hours of emergency power.

Figure 10: Bus Export Power Unit.

Hele-On 19-Passenger Fuel Cell Electric Buses

Two 19-passenger FCEBs (Figure 11) were also

acquired by the MTA from Hawaiʻi Volanoes

National Park (HAVO). These buses were converted

by U.S. Hybrid and are of similar design to the 29-

passenger FCEB. Onboard hydrogen capacity is 10

kg giving a projected range of 100 miles. These buses

are being upgraded with 40kW U.S. Hybrid fuel cells

and A123 Lithium-ion batteries using funding from

the County of Hawaiʻi.

Figure 11: HAVO 19-Passenger FCEB

Publications

This project has produced the following papers:

• 2020, A. Headley, G. Randolf, M. Virji, M.

Ewan., Valuation and cost reduction of behind-

the-meter hydrogen production in Hawaiʻi,

MRS Energy & Sustainability, Vol. 7, Paper E26.

• 2020, M. Virji, G. Randolf, M. Ewan, R.

Rocheleau. Analyses of hydrogen energy

system as a grid management tool for the

Hawaiian Isles, International Journal of

Hydrogen Energy, Vol. 45, Issue 15, pp. 8052-

8066.

Funding Sources: U.S. Department of Energy; Office

of Naval Research; NELHA; U.S. Hybrid; State of

Hawaiʻi Hydrogen Fund; County of Hawaiʻi; Energy


Contact: Mitch Ewan, [email protected]; Richard

Rocheleau, [email protected]


http://dx.doi.org/10.1557/mre.2020.20

http://dx.doi.org/10.1557/mre.2020.20









this research is to improve the durability and

conversion efficiency of novel chalcopyrite thin-film

photo-absorbers for photoelectrochemical (PEC)

production of solar fuels, aiming for a $2/kg

production cost of renewable hydrogen.

BACKGROUND: Sometimes referred as Artificial

Photosynthesis, PEC technology combines advanced

photovoltaic (PV) materials and catalysts into a single

device that uses sunlight as the sole source of energy

to split water into molecular hydrogen and oxygen. In

a typical PEC setup, the solar absorber is fully

immersed into an electrolyte solution and solar fuels

are generated directly at its surface. Fuels produced

with this method can be stored, distributed, and

finally recombined in a fuel cell to generate

electricity, with water as the only byproduct.

In 2014, the team at HNEI’s Thin Films Laboratory

teamed up with several National Laboratories (LLNL,

LBNL and NREL) and mainland academic teams

(Stanford, UNLV) to develop new semiconducting

materials for PEC water splitting, with primary focus

on chalcopyrites. This material class, typically

identified by its most popular PV-grade alloy

CuInGaSe2, provides exceptionally good candidates

for PEC water splitting. A key asset of this thin-film

semiconductor material class is its outstanding photo-

conversion efficiency, as demonstrated with

CuInGaSe2-based PV cells (>23%). In a PEC

configuration, our group has demonstrated that

chalcopyrite-based systems are also efficient at

storing solar energy into hydrogen bonds without the

need of expensive precious catalysts (Gaillard, 2013)

PROJECT STATUS/RESULTS: The HNEI’s Thin

Films Laboratory is now combining theoretical

modeling with state-of-the-art materials synthesis and

advanced characterization capabilities to provide

deeper understanding of chalcopyrite-based PEC

materials and engineer high-performance devices.

Our recent study demonstrates that alloying

chalcopyrites with sulfur can improve light collection

and increase their photo-conversion from 30% to 65%

of the theoretical limit (Gaillard, 2019). Also, we

recently demonstrated that a 3-5 nanometer thick

metal oxide or sulfide layer can be used to effectively

passivate chalcopyrites surface against

photocorrosion, improving their durability from only

few days to up to 6 weeks (Hellstern, 2019). Finally,

we are investigating new device integration schemes

involving thin-films exfoliation and bonding

techniques to transfer chalcopyrite layers onto other

solar absorbers to create multi-junction devices with

tunable properties for efficient water splitting devices

(Gaillard, 2019 presentation).

This project has produced a number of works,

including the three below:

• 2019, T.R. Hellstern, et al., Molybdenum Disulfide

Catalytic Coatings via Atomic Layer Deposition

for Solar Hydrogen Production from Copper

Gallium Diselenide Photocathodes, ACS Applied

Energy Materials, Vol. 2, Issue 2, pp. 1060-1066.

• 2019, N. Gaillard, Novel Chalcopyrites For

Advanced PEC Water Splitting, Presented at the

DOE Hydrogen and Fuel Cells Program AMR and

Peer Evaluation Meeting, April 30.

• 2013, N. Gaillard, et al., Development of

Chalcogenide Thin Film Materials for

Photoelectrochemical Hydrogen Production,

MRS Proceedings, Vol. 1558, Paper mrss13-1558-

z02-07.

Funding Source: U.S. Department of Energy

(EERE, HFTO)

Contact: Nicolas Gaillard, [email protected]



Solar Fuels Generation

1.6$eV$ 2.0$eV$ 2.2$eV$ 2.4$eV$

CuGaSe2$ CuInxGa(13x)S2$$

Bandgap tunable photoelectrodes Transferable PEC layers for efficient devices

H+ H2

H2OO 2

Widebandgap

Narrowbandgap

Substrate

Tandem PEC device concept

http://dx.doi.org/10.1021/acsaem.8b015622




https://www.hydrogen.energy.gov/pdfs/review19/p162_gaillard_2019_o.pdf

https://www.hydrogen.energy.gov/pdfs/review19/p162_gaillard_2019_o.pdf

http://dx.doi.org/10.1557/opl.2013.1084






OBJECTIVES AND SIGNIFICANCE: Methane hydrates

in deep ocean sediments and arctic permafrost

constitute an enormous energy reservoir that is

estimated to exceed the energy content of all known

coal, oil, and conventional natural gas resources. The

primary goals of this project that has been ongoing

since 2001 are to 1) support exploration of hydrate

reservoirs in seafloor sediments and arctic

permafrost; 2) support the development of safe and

practicable methods to destabilize hydrates to

produce methane fuel; and 3) advance our

understanding of the environmental impacts of

natural seeps and accidental releases of methane and

other hydrocarbons in the ocean. HNEI has also

investigated engineering applications of hydrates

including desalination and H2 storage, and promoted

many international R&D collaborations.

BACKGROUND: Research on CO2 hydrates at HNEI

began in the 1990’s as part of an international

collaboration on CO2 ocean sequestration. The

research scope was expanded to include methane

hydrates when HNEI was asked by the Minerals

Management Service (MMS) of the Department of

the Interior to participate in a study on deep oil spills.

Over time, we have conducted a host of laboratory

investigations on a wide range of topics related to

hydrates and participated in numerous oceanographic

research cruises to offshore hydrate zones.

At present, our activities are focused on the following

three areas: 1) chemical destabilization of hydrates;

2) biogeochemistry of seafloor methane hydrates; and

3) the biodegradation of methane in the ocean.

Methane hydrates can be destabilized by application

of heat, depressurization, or contact with chemical

reagents known as thermodynamic inhibitors.

Destabilization results in melting of the solid hydrate,

which releases liquid water and methane gas. Many

conventional inhibitors are expensive and/or toxic.

Our laboratory experiments evaluate the effectiveness

of various inhibitors with the goal of identifying safe

and inexpensive alternatives. Figure 1 shows a novel

facility developed by HNEI researchers to investigate

the thermochemistry of hydrates. This facility

employs a fiberoptic probe coupled into a high

pressure calorimetry test cell to permit Raman spectra

to be sampled as hydrates form and decompose. The

Raman calorimeter has provided valuable data to

assess inhibitor effectiveness.

Figure 1. Photo of the Raman calorimetry facility.

PROJECT STATUS/RESULTS: Experimental work

under this project is nearing completion. Key results

of recent work include: analysis of seismic data of

hydrate reservoirs in the Nankai Trough offshore of

Japan and determination of the effectiveness of

alternative inhibitors such as salts that occur naturally

in seawater and glycerol to dissociate hydrates. An

investigation of methane hydrate kinetics within a

sand substrate is nearing completion.

This project has produced the following publications:

• 2017, J.T. Weissman, et al., Hydrogen Storage

Capacity of Tetrahydrofuran and Tetra-N-

Butylammonium Bromide Hydrates Under

Favorable Thermodynamic Conditions,

Energies, Vol. 10, Issue 8, Paper 1225.

• 2017, K. Taladay, et al., Gas-In-Place Estimate

for Potential Gas Hydrate Concentrated Zone

in the Kumano Basin, Nankai Trough

Forearc, Japan, Energies, Vol. 10, Issue 10,

Paper 1552.

• 2016, T.Y. Sylva, et al., Inhibiting Effects of

Transition Metal Salts on Methane Hydrate

Stability, Chemical Engineering Science, Vol.

155, pp. 10-15.

• 2016, T.H. Ching, et al., Biodegradation of

biodiesel and microbiologically induced

corrosion of 1018 steel by Moniliella wahieum

Y12, International Biodeterioration &

Biodegradation, Vol. 108, pp. 122-126.


Contact: Brandon Yoza, [email protected]



Methane Hydrates

http://dx.doi.org/10.3390/en10081225

http://dx.doi.org/10.3390/en10081225

http://dx.doi.org/10.3390/en10081225

http://dx.doi.org/10.3390/en10081225

https://dx.doi.org/10.3390/en10101552







http://dx.doi.org/10.1016/j.ibiod.2015.11.027







OBJECTIVE AND SIGNIFICANCE: The primary

objectives of this study are to identify aquatic

microbes that effectively degrade hydrocarbon

pollutants in estuaries and the ocean, and to elucidate

the mechanisms of this degradation. This information

is vital to understand and assess the extent of the

environment impacts of oil and gas discharges and to

develop novel strategies to mitigate these impacts.

BACKGROUND: This project is an adjunct to the

APRISES Methane Hydrates task. Purposeful (e.g.,

for natural gas recovery) or accidental destabilization

of seafloor hydrates will release methane into the

oceanic water column. In addition, many commercial

and DoD activities result in hydrocarbon

contamination of the ocean and estuarine

environments. Under these types of scenarios,

bacterial and fungal communities in the water are

known to play a key role in ameliorating the impacts

of the polluting hydrocarbons species.

Laboratory experiments have been conducted to

identify microbes that can metabolize and remove

hydrocarbon contaminants from aquatic environ-

ments and to investigate the key pathways and

mechanisms of this process. Figure 1 is a microscope

photograph of a species of fungus found in Hawaiʻi

that can degrade hydrocarbons, which was isolated

and identified in this study.

Figure 1. Moniliella wahieum (ATCC MYA-4962) a

hydrocarbon degrading fungus that has been isolated and

characterized in Hawaiʻi.

PROJECT STATUS/RESULTS: This project is

ongoing. Recent results are available in the following

peer-reviewed publications:

1. 2020, J. Liang, et al., Rapid granulation using

CaSO4 and polymers for refractory

wastewater treatment in up-flow anaerobic

sludge blanket reactor, Bioresource

Technology, Vol. 305, Paper 123084.

2. 2018, Q. Wang, et al., Treatment of petroleum

wastewater using an up-flow anaerobic sludge

blanket (UASB) reactor and turf soil as a

support material, Journal of Chemical

Technology and Biotechnology, Vol. 93, Issue

11, pp. 3317-3325.

3. 2017, C. Ye, et al., Cometabolic degradation of

blended biodiesel by Moniliella wahieum

Y12T and Byssochlamys nivea M1,

International Biodeterioration & Biodegradation,

Vol. 125, pp. 166-169.

4. 2016, C-M. Chen, et al., Laboratory studies of

rice bran as a carbon source to stimulate

indigenous microorganisms in oil reservoirs,

Petroleum Science, Vol. 13, Issue 3, pp. 572-583.

5. 2016, T.H. Ching, et al., Biodegradation of

biodiesel and microbiologically induced

corrosion of 1018 steel by Moniliella wahieum

Y12, International Biodeterioration &

Biodegradation, Vol. 108, pp. 122-126.

6. 2013, R.B. Coffin, et al., Spatial variation in

shallow sediment methane sources and cycling

on the Alaskan Beaufort Sea Shelf/Slope,

Marine and Petroleum Geology, Vol. 45, pp. 186-

197.

7. 2013, R.M. Harada, et al., Diversity of Archaea

communities within contaminated sand

samples from Johnston Atoll, Bioremediation

Journal, Vol. 17, Issue 3, pp. 182-189.


Contact: Brandon Yoza, [email protected]



Microbial Degradation of Hydrocarbons in Marine and Estuarine Environments

http://dx.doi.org/10.1016/j.biortech.2020.123084




http://dx.doi.org/10.1002/jctb.5694







http://dx.doi.org/10.1007/s12182-016-0104-7

http://dx.doi.org/10.1007/s12182-016-0104-7

http://dx.doi.org/10.1007/s12182-016-0104-7





http://dx.doi.org/10.1016/j.marpetgeo.2013.05.002



http://dx.doi.org/10.1080/10889868.2013.808984

http://dx.doi.org/10.1080/10889868.2013.808984

http://dx.doi.org/10.1080/10889868.2013.808984





this project was to determine the feasibility and

benefits of modifying the current energy system at

Natural Energy Laboratory of Hawaiʻi Authority

(NELHA)’s Hawaiʻi Ocean Science and Technology

(HOST) Park to enable it to operate as a microgrid (or

a number of microgrids) connected to the Hawaiʻi

Electric Light Company (HELCO) electric grid

system, or as a stand-alone facility. The study will

determine those distribution system configurations

providing optimal benefit to NELHA, the HELCO

grid, and both together. A secondary objective is to

maximize the use of renewable energy resources

available within the HOST Park.

Figure 1. NELHA’s HOST Park site and existing HELCO

primary distribution feeder.

BACKGROUND: Microgrids, especially those

integrating renewable energy resources, are of

interest in Hawaiʻi for their potential to enhance the

reliability of the microgrid site and host grid, to

increase energy assurance, improve security, and

potentially reduce cost and carbon footprint.

Microgrids can also improve resilience against both

manmade and natural disruptions. The Governor of

Hawaiʻi signed Act 200, which directed the Hawaiʻi

Public Utilities Commission (PUC) to open a

proceeding to establish a microgrid services tariff to

encourage and facilitate the development and use of

microgrids throughout the State. NELHA’s HOST

Park facility has been identified by the PUC as a

potential microgrid demonstration site for advanced

technologies to enable grid resiliency. Along with

techno-economic resource optimization, HNEI will

identify regulatory and policy issues currently in

place that hinder the development of microgrids and

offer modifications to those regulations and policies

for future action.

To achieve the overall project objectives, a power

system requirements analysis of the HOST Park

based on NELHA’s energy projections for a 10-year

period will be conducted. Both the technical and

regulatory/policy opportunities and barriers will then

be assessed, with potential on-site distributed

generation, energy storage, power management, and

control technology alternatives evaluated to identify

the most promising ones applicable to a microgrid or

microgrids at the NELHA HOST Park. The work will

deliver microgrid conceptual design options that meet

NELHA’s technical and economic power

requirements over the 10-year planning horizon.

PROJECT STATUS/RESULTS: HNEI’s GridSTART, in

collaboration with NELHA staff, identified the

existing and planned power generation and

distribution infrastructure and requirements for the

HOST Park. This work included a review of

NELHA’s HOST Park utility metered accounts,

historical energy use and power demand, utility rate

structures, distribution infrastructure, critical load

priorities, load service reliability, existing emergency

and renewable generation resources, and forward

projected power needs. An integrated assessment of

these energy system elements with the HELCO

distribution infrastructure that serves the HOST Park

has yielded conceptual microgrid design options.

Detailed feasibility, techno-economic analysis, and

optimization of these conceptual microgrid options

continue.

Figure 2. Potential HOST Park microgrid configuration for

extended utility grid outage.

Funding Source: Hawaiʻi State Energy Office via

NELHA

Contact: Leon Roose, [email protected]


Hawaiʻi Natural Energy Institute Research Highlights Grid Integration & Renewable Power Generation

NELHA HOST Park Microgrid Analysis




OBJECTIVE AND SIGNIFICANCE: HNEI is supporting

Marine Corps Base Hawaiʻi (MCBH) in completing

its Installation Energy Security Plan (IESP) to

enhance installation energy resilience and improve

mission assurance. The IESP will document the

current and future energy security requirements of

MCBH, its ability to meet those requirements, and

plans to address high priority gaps. It will take into

account resource constraints, statutory mandates,

executive policy, and service-level priorities.

Figure 1. Marine Corps Base Hawaiʻi at Kāneʻohe Bay.

(Photo Credit: MCBH)

BACKGROUND: On May 30, 2018, the Office of the

Assistant Secretary of Defense Energy, Installations,

and Environment (OASD-EI&E) issued the

memorandum “Installation Energy Plans – Energy

Resilience and Cybersecurity Update and Expansion

of the Requirement to All DoD Installations,”

mandating an IESP be prepared for MCBH. The IESP

must take into account the capacity, reliability, and

condition of the existing energy infrastructure on base

and the ability to meet future growth requirements.

The IESP is envisioned to discuss, compare and

contrast alternatives for energy security and

resiliency, and recommend technical strategies and

solutions. The solutions are to be based upon

technologies that are already proven commercially

viable and ready-to-go. Thus, it’s intended to deliver

an actionable energy plan for MCBH with a focus on

resilient, proven, and economically viable energy

systems ready for implementation. HNEI’s

GridSTART and MCBH are cooperating through

regular interaction and exchange to secure necessary

information on the electrical infrastructure, plans,

operations, critical load priorities, relevant base

studies/assessments, and the like to facilitate HNEI’s

support of the IESP. The IESP includes seven stages

and follows the planning framework shown in Figure

2.

PROJECT STATUS/RESULTS: An initial draft report

of the IESP including stages 1, 2, 3, and 4 has been

delivered to MCBH and is currently under review.

HNEI continues its work on stage 5 of the IESP. This

stage proposes solutions addressing the installation’s

energy resilience requirement of fourteen days

without commercial power. Alternative microgrid

designs are being developed and assessed, including

a microgrid solution that powers the entire base and

smaller microgrids that maintain power to base

priority loads. Figure 3 illustrates a conceptual

microgrid design that utilizes the existing rooftop PV

at MCBH and proposes additional generation and

energy storage resources to power the entire base

through an extended utility service outage.

Figure 3. Conceptual design of a full base microgrid.





Marine Corps Base Hawaiʻi Installation Energy Security Plan

Figure 2. IESP process flow chart.




OBJECTIVE AND SIGNIFICANCE: This summary

highlights the findings from the evaluation of three

grid-tied Battery Energy Storage Systems (BESS)

each addressing different issues arising increasing

renewable energy penetration levels. The three BESS

in this study facilitated the discovery of benefits as

well as a number of unexpected adverse

consequences arising from this relatively new

technology on isolated grids.

BACKGROUND: HNEI entered into agreements with

electric grid utility companies on the Big Island of

Hawaiʻi, Oʻahu, and Molokaʻi to install and test three

BESS. Under the agreements, HNEI procured the

systems and developed control algorithms.

Ownership was transferred to the utilities after

commissioning while HNEI retained multi-year data

access and testing rights. The first system was

installed on the Big Island at a windfarm in the town

of Hawʻi, the second on an industrial circuit with high

PV penetration on Oʻahu, and the third on the island

of Molokaʻi at its only power station.

The three BESS were designated to test different grid

services. The first 1 MW, 250 kW-Hr BESS was

installed on the Big Island of Hawaiʻi and provided

either frequency response or wind power smoothing

to the 180 MW (peak) grid that hosts 119 MW of

renewable capacity. A second 1 MW, 250 kW-Hr

BESS installed on Oʻahu demonstrated power

smoothing and voltage regulation on a highly variable

industrial circuit with large loads and significant PV

penetration. A 2 MW, 397 kW-Hr BESS was installed

on the island of Molokaʻi and demonstrated fast

frequency response on a low-inertia 5.5 MW (peak)

grid hosting about 2.3 MW of distributed PV.


Hawaiʻi (“Big Island”) BESS:

The Big Island BESS showed significant durability.

After 7,500 equivalent full cycles over ~7 years of

service the system still operates to specification with

only minor repairs. While providing wind smoothing,

there were several events where the BESS acted in

opposition to the grid’s frequency regulation needs so

the work focused on use of the BESS for frequency

regulation. The chart below shows an example of the

BESS absorbing power in the beginning and at the

end of an under frequency event.

While providing frequency response, the BESS

signficantly reduced grid frequency variability (top

chart below). The use of deadband allowed the BESS

to provided strong grid service while minimizing

cycling. Cycling was characterized by measuring

energy throughput of the BESS. Energy throughpout

with and without deadband is shown in the bottom

chart below. The nomenclature, <σOFF> indicates the

mean variability of grid frequency for a 20-minute

period just before the BESS was turned on for another

20 minutes, whose variability is denoted as <σON>.

0 10 20 30 40 50 601500

2000

2500

3000

3500

4000

4500

5000

5500

6000

Time [Minutes from 10:00 AM]

Hawi Wind Smoothing 10/21/2015

Real P

ow

er

[kW

]

Raw Wind Power

Smoothed Wind Power


Grid-Scale Battery Testing



Island of Oʻahu BESS

The figure below shows the impact of the Oʻahu

BESS on an industrial circuit’s voltage. 500V was

artificially added to these traces to avoid overlapping.

The variability of the blue and green traces was about

40V when the BESS was offline or only providing

power smoothing. The variability dropped to 30V for

when the BESS is providing voltage regulation by

adjusting its reactive power (red line). When both

power smoothing and voltage regulation are used, the

variability drops to less than 20V. The voltage

regulation service reduced the substation’s load tap

changer operations by about 80%. However, the

voltage regulation doubled the power consumption of

the BESS from 20 kW to 40 kW and excess heating

caused isolation faults in the BESS system. This

BESS was idle for a number of years prior to

installation. Moisture absorbed in the capacitors

needed to filter harmonics was the cited cause of an

early failure of the system.

Island of Molokaʻi BESS

The Molokaʻi system provided several significant

insights into the limits of fast frequency response

BESS on small, low inertia electric grids. Due to the

low system inertia, the grid frequency can swing

quickly when relatively small electrical events occur.

When those frequency swings breach PV

disconnection thresholds, this new contingency

compounds the original problem. Early testing also

showed that, due to the low inertia, fast frequency

response required the BESS to have a response time

on the order of 50 milliseconds, something that did

not exist in the market. A BESS providing fast

frequency response sources real power to the grid

when the grid frequency is low and absorbs real

power from the grid when the frequency is high.

Latency in this process caused instability on the low

inertia grids. This result has important implications

for use of BESS on any low inertia system.

The BESS generally provided helpful support, as

shown in the figure below where the BESS responded

to a frequency drop and then slowly handed the

control back to the thermal generators. A review of

the data indicates that the BESS likely prevented a

number of outages, although there were some

anomalies that caused enough concern to the utility so

that the 2 MW BESS was limited to 1 MW or less.

Specifically, high-resolution voltage data suggests

that the cause of these anomalies is related to

frequency measurement errors that might also occur

in other inverters (e.g., grid-tied PV inverters) on low

inertia grids. Several grid meters from disparate

manufacturers show a strong drift in measurement

sampling times during grid contingencies, such as

faults. This topic is currently being documented in a

paper.


Contact: Marc Matsuura, [email protected];

Richard Rocheleau, [email protected]


0 5 10 15 2012

12.5

13

13.5

14

14.5

15

Time [Hours of Day]

Voltage [

kV

]

BESS Off

Power Smoothing Enabled; No Voltage Regulation

No Power Smoothing, Voltage Regulation Enabled

Power Smoothing and Voltage Regulation Enabled





OBJECTIVE AND SIGNIFICANCE: As summarized in

the “Grid-Scale Battery Testing” project summary,

a fast responding Battery Energy Storage System

(BESS) was installed and operated to provide fast

frequency response on a low-inertia grid on the island

of Molokaʻi. Lessons learned from that system that

could impact industrial standards for metering and

frequency measurement during electrical transients

on low inertia grids.

BACKGROUND: HNEI and Maui Electric entered into

an agreement to install and test a 2 MW, 397 kW-Hr

BESS on the island of Molokaʻi. The electric grid on

Molokaʻi is ~5.5 MW (peak) with ~2.3 MW of

distributed photovoltaics (PV). The significant PV

penetration complicates grid operations; they

automatically disconnect when the grid frequency is

below a threshold, exacerbating any loss of

generation, and they displace traditional generation

which has natural mechanical inertia.

Because of the low system inertia, the island’s grid

frequency can swing quickly when relatively small

electrical events occur. When those swings exceed

PV disconnection thresholds, the loss of PV

generation compounds the original problem.

Modeling and experiments also showed that low grid

inertia also means that any BESS providing fast

frequency response would be required to have a

response time on the order of 50 milliseconds to be

effective, something that did not exist in the market.

A BESS providing fast frequency response provides

real power to the grid when the grid frequency is low

and absorbs real power from the grid when the

frequency is high. Latency in this process can cause

instability on low inertia grids.

HNEI funded a BESS manufacturer and an inverter

manufacturer to redesign the control path to minimize

the system response time as much as possible. The

new controls allowed the inverter to measure grid

frequency directly rather than wait to receive real

power commands from the battery's controller. The

redesign reduced BESS response to an event from

around 300ms to within 58 milliseconds (typical)

which, to the best of our knowledge, is the fastest

BESS response reported to date. Live grid testing

showed that the redesigned BESS effectively reduced

grid instability resulting from conflicts with the

island’s diesel generators.

The Molokaʻi BESS has been in service since May

2017. As the system’s authority (maximum allowable

power response) was raised, expected power outages

were increasingly avoided. Over the duration of the

project, the Molokaʻi BESS has responded to many

grid events. Based on historical comparisons, the

BESS response has eliminated a number of potential

grid outages. However, some anomalies were also

amplified by the fast response. One anomaly was a

fast oscillation in BESS real power and grid

frequency. This oscillation was too fast to be

explained as conflicts between the BESS and the

diesel generators. An oscillation detector was

incorporated as a patch into the BESS control

software to arrest operations until the oscillations

cleared. While the source of the oscillations is not

fully understood, a review of laboratory data as well

as high resolution measurement on the grid suggests

the problem results from how the inverter measures

grid frequency. There have been several oscillation

events and findings that will be discussed in an up-

coming paper. One notable event, that provides

insights into the problem from August 11, 2020 is

discussed further below.

PROJECT STATUS/RESULTS: On August 11, 2020,

the BESS responded to a generator outage, supplying

real power to mitigate the drop in frequency.

However, instead of resolving the problem, fast

oscillations in real power were detected and the BESS

service was halted. This caused one of the other diesel

generators to respond by sourcing more power. Less

than a second later, the BESS again began to source

real power until another oscillation started, causing

the BESS to halt output again. This cycle repeated

several times and caused the generator to exceed its

power rating of 2.2 MW. This event, shown in Figure

1 below, prompted re-examination of controlled

laboratory testing that had been performed on the

inverter prior to installation on Molokaʻi.


Fast Frequency Response Battery on a Low-Inertia Grid

https://www.hnei.hawaii.edu/wp-content/uploads/Grid-Scale-Battery-Testing.pdf



As depicted in the Figure 2 on the right, examination

of the laboratory data showed some anomalous

behavior. An experiment was run during which the

inverter was set to absorb a constant 200 kW while

the true frequency (green trace in the figure below)

was held at 58 Hz for the first ~12 minutes of the test.

The frequency was then ramped up gradually to 62

Hz. While ramping up, the inverter’s estimate of

frequency (blue trace) diverged from the true

frequency. This is shown more clearly in the

expanded scale in Figure 2b showing a clear

difference between 60.5 Hz and 60.9 Hz. This

behavior has now been observed both in the lab and

field for various frequency and power combinations.

Also, since grid scale inverters are not normally used

to directly measure frequency, relying instead on

external commands, we are not able to comment at

this time about the prevalence of this issue in other

types of inverters.

The oscillations shown in Figure 1 occurred when the

grid frequency was just below 60 Hz with the inverter

supplying ~800 kW, a point that could not be tested

in the laboratory. The plausibility of such frequency

measurement errors causing oscillations on a small

grid in a closed-loop with a BESS is under

investigation and will be reported on. Funding Source: Office of Naval Research

Contact: Marc Matsuura, [email protected];



0 10 20 30 40

58

60

62

64

Time in Test [Sec]

Fre

quency [

Hz]

In-lab Frequency Sweep

Inverter Meas.

"True" Freq.

15 15.5 16 16.559.5

60

60.5

61

61.5

62

Time in Test [Sec]

Fre

quency [

Hz]

Expansion of Above

a)

b)





OBJECTIVE AND SIGNIFICANCE: HNEI's

GridSTART is developing a DC-based microgrid on

Coconut Island, home to UH’s Hawaiʻi Institute of

Marine Biology (HIMB), in Kāneʻohe Bay, Oʻahu.

The project objective is to demonstrate the reliability,

resilience, and energy efficiency of a DC microgrid

serving two buildings on Coconut Island. The system

is intended to support critical building loads during

grid supply interruptions, while also providing clean

electrified transportation options powered primarily

by rooftop solar energy. Results and lessons learned

from this project can be utilized for the design and

development of future DC-based microgrids at other

locations in Hawaiʻi or abroad.

Figure 1. DC microgrid project site on Coconut Island,

Kāneʻohe Bay, Oʻahu, Hawaiʻi.

BACKGROUND: Among HIMB’s goals is for the

island and its research facilities to serve as a model

for sustainable systems. Thus, it serves as an ideal site

for a renewable energy technology-based test bed that

represents a remote location vulnerable to energy

disruption, yet serving critical power needs essential

to its mission. Key project goals include:

• Adoption of innovative new energy efficient and

reliable clean energy technologies;

• Increase energy sustainability;

• Reduce dependence on the local utility and the

existing aged undersea electrical service tie to the

island;

• Provide a research platform to study DC

microgrid technologies (e.g., microgrid

controller, energy storage, and DC powered

appliances) in a tropical coastal environment; and

• Support solar powered all-electric land (E-car)

and sea based (E-boat) transportation options.

PROJECT STATUS/RESULTS: HNEI, in collaboration

with the Okinawa Institute of Science and

Technology (OIST) and the PUES Corporation,

completed the development and deployment of a DC

powered E-car, E-boat, and portable emergency

power source using a swappable battery storage

system primarily supplied by a new 6.2 kW rooftop

solar PV system. Additional microgrid elements

including DC lighting, DC air conditioning, DC-DC

converters developed by the University of Indonesia

(a research partner), 8 kW/8 kWh li-ion battery

energy storage system, HNEI’s GridSTART custom-

built DC microgrid controller, power meters and data

collection equipment, and balance of system

equipment and infrastructure are in an advanced stage

of procurement and installation. A schematic of the

DC-based microgrid test bed is shown in Figure 2.





Coconut Island DC Microgrid

Figure 2. DC microgrid single line diagram.




OBJECTIVE AND SIGNIFICANCE: The project

objective was to convert an existing off-grid solar PV

system comprising 5.1 kW PV panels, battery storage

and a backup fossil fueled generator, into a more

efficient “smart” nano-grid utilizing site-scale

automated load and demand management strategies

to minimize wasted generation, while eliminating the

need for fossil fuel backup.

BACKGROUND: From 2013-2018, Ka Honua

Momona (KHM), a not-for-profit community

organization in Kaunakakai, Molokaʻi operated from

an off-grid system consisting of 18 PV panels, dual

7200-watt Outback inverters, 40 kWh of lead acid

storage, and a fossil-fuel back-up generator. KHM

found that their renewable energy was not used

efficiently largely due to varied daily site utilization

patterns that range from a very low baseline load (e.g.,

internet router and refrigerator) to a high load (e.g.,

large events utilizing air conditioning, lighting, and

kitchen loads) that exceeds generation and storage

capacity.

To help mitigate inefficiencies in generation and

storage and stabilize the nano-grid, HNEI identified

three goals:

• To test, compare, and utilize three 9 kWh

Sunverge integrated energy storage systems in an

off-grid environment;

• To pilot a “smart” generation schema to

automatically redirect excess solar energy

generation (load dump) to other loads that would

be useful to KHM such as water heating and

water distillation; and

• To identify practical design issues when using

multiple battery banks and multiple inverters.

PROJECT STATUS/RESULTS: HNEI implemented a

“smart” strategy installing water heaters as a variable

load for excess generation. Two water heaters use

small, Heliatos™ solar thermal water heaters to

provide nominally sufficient hot water for the baths.

The solar thermal hot water is then augmented by

Sunverge integrated energy storage units after their

batteries are fully charged and are in “float”

condition. This load diversion is precisely controlled

by solid state auto transfer switches that transfer

power to the water heaters when the battery voltages

are one volt below “float” voltage and will cutout load

diversion when the batteries are two volts above low

battery cutout (LBCO).

On the power supply side, PV panels initially charge

the primary battery banks. Once the primary batteries

reach full capacity, a solid state transfer switch that

detects voltage shifts the solar generation to a

secondary set of batteries at predetermined battery

voltage condition. As these secondary batteries reach

full capacity the energy is redirected a third 50 gallon

water heater or a small water distillation system,

thereby utilizing renewable energy that would have

been wasted otherwise.

This off-grid system was designed to adapt to highly

variable usage patterns and load conditions. This

project is ongoing through December 2020.


Contact: Jim Maskrey, [email protected]



Ka Honua Momona: Maximizing Efficiency of Off-Grid Nano-Grid





the research activity is to synthesize a full set of

disaggregated solar photovoltaic (PV) and customer

load data from a limited number of field

measurements to enable more realistic distribution

feeder modeling and state analysis for circuits with

high distributed PV penetration. Actual field metered

measurements of customer load and PV system

production is very limited today, yet effective circuit

power flow modeling requires the representation of

the individual time-varying energy production and

demand profiles at all electrical buses. This work

supports the development and testing of distributed

control algorithms for distributed energy resources on

a feeder with high penetration of distributed PV.

BACKGROUND: Under the earlier U.S. Department of

Energy funded Maui Advanced Solar Initiative,

HNEI deployed approximately sixty (60)

distribution-level power monitoring devices to

capture high resolution data at key nodal points

located at distribution service transformers, PV

inverters, and residential homes. In conjunction, a

detailed electrical model was developed as shown in

Figure 1. The rooftop PV systems and customer loads

are marked with green and red circles, respectively.

This feeder serves approximately 800 customers, with

a total installed rooftop PV capacity of approximately

2 MW and a daytime minimum feeder load of 975

kW, a PV penetration level of more than 200%.

Figure 1. Maui Meadows distribution circuit.

PROJECT STATUS/RESULTS: HNEI’s GridSTART

developed a spatial-temporal algorithm to estimate

the PV generation at 280 nodal points based on

limited field collected data of nearby PV systems. The

PV data set (field and synthesized), total feeder net

load, and measured net load at each distribution

service transformer are the inputs to the stochastic

data estimation method for synthesizing gross load at

distribution service transformers where field data was

not available. The data flow is shown in the diagram

below.

Figure 2. Data flow of PV and load data synthesis.

Validation of the synthesized load and PV data was

achieved by injecting it along with the limited field

measurements into the electrical model and

comparing the voltages from the power flow with the

voltages measured in the field. The results are

illustrated in Figure 3 below with mean errors for

each transformer voltage ranging between 0.16% to

1.47%.

Figure 3. Voltage magnitude error between simulation

and field measurement.

The results of this research will be reported in part in

a manuscript that was submitted for IEEE’s 2021

Conference on Innovative Smart Grid Technologies.





Load and PV Data Synthesis




OBJECTIVE AND SIGNIFICANCE: This project’s

objective is to develop advanced forecasting methods

and technologies to predict solar photovoltaic (PV)

power generation from minutes to days ahead.

Knowledge of PV system future output will allow

grid operators and grid management systems to

proactively address the inherent variability of solar

power. Day ahead (DA) forecasts support unit

planning and scheduling, while hour ahead (HA)

forecasts support unit dispatch and operational

reserve management, and minute ahead (MA)

forecasts predict the timing and magnitude of

significant PV ramp events. Solar forecasts also

provide visibility and situational awareness for

distributed behind the meter solar systems, helping to

minimize reliability issues and disruptive events and

manage the cost of grid operations with increasing

levels of PV interconnected to the electric grid.

Figure 1. Irradiance observations and PV power

measurements from the UH FROG Building on January

30, 2020.

BACKGROUND: Power output from PV systems is

directly related to the power of the sunlight striking

the panel, measured as irradiance. Solar irradiance at

the top of the atmosphere varies slowly and

predictably, modulated by Sun-Earth geometry and

solar variability. Solar irradiance at ground-level

varies quickly and erratically, modulated by the

absorption and scattering of sunlight by clouds, fog

and haze, as well as other particulates, such as dust,

ash, and smog. The state of these particles is

controlled by complex, nonlinear, and dynamic

atmospheric processes, which make PV power output

in most cases highly variable and difficult to predict.

A sample day of irradiance observations and

measurements of PV output from the UH FROG

Building are shown in Figure 1.

HNEI has developed a multi-scale, solar forecasting

system capable of monitoring irradiance in near real-

time and generating PV power forecasts from minutes

to days ahead. This system is fully automated,

generating predictions without human intervention.

For DA forecasts (longer than 6 hours ahead),

numerical weather prediction (NWP) models are

required to account for turbulent atmospheric

processes. DA forecasts are generated from a specific

configuration and augmentation of the Weather

Research and Forecasting (WRF) system designed for

solar energy applications.

Geostationary satellite images provide consistent

monitoring of regional atmospheric conditions, while

ground-based sky camera images monitor local

conditions at high resolution (Figure 2). From these

images we determine the position, velocity, and

optical properties of cloud formations. This

information is used to drive cloud dynamics models

that estimate future cloud conditions and irradiance at

HA and MA time scales.

Using ensemble methods, DA, HA, and MA

irradiance predictions are combined to generate

probabilistic irradiance forecasts. These probabilistic

forecasts are used to drive PV simulation tools to

predict PV power.

Figure 2. Sample irradiance map from GOES-17 images.


Solar Power Forecasting



PROJECT STATUS/RESULTS: HNEI continues

development of an irradiance mapping and prediction

instrument for high-resolution irradiance nowcasting

and MA forecasting. The instrument is designed for

low production cost, wireless operation, and self-

monitoring. The latest version of the instrument

incorporates more robust electronics and increased

computational power to allow for edge computing

functionality. A prototype instrument is currently

deployed on the UH campus, a sample image can be

seen in Figure 3.

Figure 3. Sky image taken from the UH Mānoa campus

on October 25, 2020.

The HNEI solar forecasting system is actively

generating operational probabilistic forecasts for the

Hawaiian Islands.

Each night, a regional 24-hour ahead forecast is

generated from NWP. During daylight hours, a

regional 6-hour ahead forecast is generated from

NWP and GOES-West images. This forecast is

updated every 10 minutes to include information the

most recent satellite images.

Tools for forecast data distribution and web-based

visualization have been added to the system. The

prototype visualization system focuses on the Natural

Energy Laboratory of Hawaiʻi Authority (NELHA)

site (on the island of Hawaiʻi), where the National

Renewable Energy Laboratory (NREL) maintains

instrumentation that provide realtime irradiance

observations. NELHA site forecasts and realtime

observations can be viewed at:

http://128.171.156.27:5100/hawaii/. Figure 4 shows

sample output from the visualization system for

September 25, 2020 at 12:22 PM HST.

Figure 4. Sample output from the forecasting

visualization system for the NELHA site. The

probabilistic forecast and ensemble distribution are

shown in green, while realtime irradiance observations

are shown in blue. The black solid line indicates the

current time.

Funding Source: Office of Naval Research; KERI;

U.S. Department of Energy, UI-ASSIST

Contact: Dax Matthews, [email protected]


http://128.171.156.27:5100/hawaii/




OBJECTIVE AND SIGNIFICANCE: Under this joint

project between HNEI and Maui Electric Company

(MECO) a custom controlled Dynamic Load Bank

(DLB) was deployed with the objective of

demonstrating a reliable and inexpensive means to

prevent the baseload diesel generators from operating

below their minimum dispatch level during periods of

high solar generation. The system enabling the grid

connection of additional rooftop PV on Molokaʻi

island, beyond that originally allowed by the utility.

Continuing research in controls is intended to deliver

additional grid value from this asset, such as rapid

response to system dynamic events. Project lessons

will support enabling high penetration of distributed

PV systems on microgrids and island power systems.

BACKGROUND: Among the challenges faced by

utilities to integrate very high levels of rooftop solar

PV on isolated island grids is maintaining a minimum

reliable operating level of diesel generators during

times of high PV production. High PV production can

force generators below their required minimum

operating point, with the uncontrolled “excess

energy” produced by the PV systems degrading grid

reliability and operating risk to unacceptable levels.

Moloka‘i reached its system-wide rooftop PV hosting

capacity in 2015, resulting in a 700 kW queue of new

customer applications for rooftop PV. Analysis

showed that the potential for excess energy

production by proposed rooftop PV systems held in

the queue would occur very infrequently. By

absorbing a mere 3.9 MWh of excess solar energy

with the DLB, additional annual production of a

significant 1.1 GWh of clean solar energy is enabled,

with a commensurate reduction in fossil energy use.

Figure 1. Analysis showing infrequent events of rooftop

PV annual excess energy production requiring mitigation

by the DLB.

Functioning as a grid “safety valve” to manage

infrequent events of excess solar energy production,

the DLB solution allowed the grid connection of

approximately 100 new customer-sited rooftop PV

systems at a cost far below that of energy storage,

while ensuring adequate operating reserves and grid

stability on the island. The installed DLB and its

controller are shown in Figure 2.

Figure 2. a) The DLB installed at MECO power plant on

Moloka‘i; b) RTAC controller with the smart meter used

for tests.

PROJECT STATUS/RESULTS: DLB control

algorithms for excess energy absorption were

developed, lab tested, and validated via grid

simulation. The DLB system was then installed,

tested, and placed in service at the MECO power plant

on Moloka‘i. Successful operation of the DLB

allowed 700 kW of new customer-sited distributed

PV to be grid tied, following a 3-year period of no

new PV system additions. HNEI GridSTART is

continuing its valued partnership with MECO to

develop additional grid stabilizing control algorithms

that can rapidly react to system disruptions, such as

sudden loss of generation or load rejection events.

Stacking added functionality such as automatic

frequency response will increase both utility and

customer value return on the very modest investment

in DLB technology.





Dynamic Load Bank for Islanded Grid Solutions





this project is to develop a low-cost device and system

that can provide enhanced situational awareness

allowing tighter, localized coordination of distributed

energy resources (DERs) such as rooftop solar

photovoltaics (PV). This is important for Hawaiʻi

because as power generation and ancillary services

become more decentralized and variable, there will be

a need for enhanced measurement, data analytics, and

distributed controls near the grid edge. Field devices

such as advanced meters, line sensors, and secondary

reactive power (var) controllers are all part of

Hawaiian Electric Companies’ Grid Modernization

Strategy, and this project has the potential to provide

significant advancements in these areas beyond the

commercial state of the art.

BACKGROUND: Grid edge technology has the

potential to relieve voltage constraints with local

context-aware volt/var control, identify and help

mitigate local thermal violations through energy and

load shifting, provide data for more refined and

readily updated PV hosting capacity analysis, identify

power quality issues such as harmonic distortion from

increasing amounts of power electronic devices, and

assist in fault location and anomaly detection, such as

pending transformer failure and unmetered loads.

This system offers a high-tech, flexible research-to-

commercialization platform that can be programmed

to support these use cases and more. It offers high-

fidelity voltage and current measurement, numerous

communications options, low-latency event-driven

messaging, precise GPS-based timing, backup power

supply, and powerful processing capabilities for real-

time data analysis, all within a small weather resistant

enclosure.

PROJECT STATUS/RESULTS: ARGEMS devices

have been successfully deployed at the UH Mānoa

campus, Arizona State University, Chulalongkorn

University (Thailand), and in Okinawa, Japan. The

latest version is shown in Figure 1 and examples of

analysis and visualization are shown in Figure 2.

The system is currently patent pending (via UH’s

Office of Technology Transfer) and commercial

pathways are being explored. Discussions regarding

potential use cases and demonstrations have been

initiated with utilities in Hawaiʻi, Alaska, and

Thailand. Assembly is now performed commercially.

Costs are expected to be competitive with traditional

distribution service transformer monitors.

The project has enabled and fostered new

collaborations and funded research and it has been

featured in educational and outreach activities. It has

supported research on distributed volt/var control

(DURA project led by Arizona State University) and

optimal electric vehicle scheduling and charging

(vehicle to grid demonstration, with Hitachi).

Fourteen (14) undergraduate students and six

international interns have been involved. It has been

shared with the public through ThinkTech Hawaiʻi,

SOEST’s Open House, and UH Sea Grant’s Voices

of the Sea.

Figure 1. ARGEMS devices ready for research

collaboration.

Figure 2. Analysis and visualization of real-time data.

Funding Source: Office of Naval Research; Defense

University Research-to-Adoption (DURA) via

Arizona State University

Contact: Kevin Davies, [email protected]



Advanced Real-Time Grid Energy Monitor System (ARGEMS)





this project was to demonstrate conservation voltage

reduction (CVR) as an effective ways to save energy.

The main principle of CVR is that energy and peak

demand can be lowered by up to 0.9% for each 1%

reduction in voltage level.

BACKGROUND: The primary value proposition of

CVR implementation – reduced energy use by more

effective management of customer service voltage

with an expected reduction in energy consumption in

the range of 0.7% to 0.9% for every 1% reduction in

voltage. Working in close collaboration with Marine

Corps Facilities personnel in Okinawa, seven

distribution service transformers on a branch of the

13.8 kV circuit serving the Plaza Housing complex

was identified for CVR field test and evaluation.

Figure 1. CVR Demonstration Single-Line Diagram.

The CVR controlled feeder section is isolated with a

new voltage regulator (VR) to control the voltage at

“downstream” service transformers, essentially

behaving like a substation transformer load tap

changer (LTC) for the section of the feeder under test.

The LTC action of the VR shifts the voltage profile

of the feeder up or down, but is unable to manage

individual low or high voltage points along the feeder

path. Voltage reduction by the LTC is thus

constrained by the minimum voltage point along the

feeder. HNEI has patented and field demonstrated a

method of localized voltage management with an

advanced CVR device to: (1) smooth the voltage

profile; (2) boost the lowest voltage at a distribution

service transformer, thereby allowing the LTC to

further shift the entire feeder voltage down; and (3)

provide maximum CVR benefit for all customers.

PROJECT STATUS/RESULTS: Utilizing HNEI

hardware-in-the-loop (HIL) laboratory platform,

testing and validation of the CVR control algorithm

developed by HNEI’s GridSTART, including

communication between the controller and field

meters to be located at service transformers was

completed.

Figure 2. CVR real-time HIL test set-up.

Multiday real-time HIL simulations using field

voltage measurements collected from the project site

were used to ensure robust and reliable operations of

the HNEI-controller and algorithm under a full range

of load conditions.

Figure 3. Voltage Profiles with CVR on and off.

Field design and construction of all CVR system

components and a 5.8kW rooftop PV system is

complete, with civil/structural work performed by

Navy Seabees. Project operational commissioning is

pending the lifting of COVID-19 travel restrictions.

Figure 4. Project construction by Navy Seabees and new

PV system.

Funding Source: UH ARL; Office of Naval Research




Advanced Conservation Voltage Reduction Development & Demonstration





this project is to support the long-term goal of

designing highly scalable technologies for

distribution systems to operate reliably and securely

with extremely high penetration of distributed energy

resources. The results from this three year project,

conducted by HNEI as a subawardee to the University

of Central Florida (UCF), will provide a scalable

solution that can be adapted to grids of various sizes,

and facilitates the integration of additional distributed

energy resources.

BACKGROUND: The project overview is summarized

in Figure 1. The expected outcomes of this project

includes:

• A modular, plug-and-play and scalable

Sustainable Grid Platform (SGP) for real-time

operation and control of the distribution network;

• Advanced distribution operation and control

functions to manage extremely high penetration

solar PV generation (installed PV capacity >

100% of distribution feeder peak load) in a cost-

effective, secure, and reliable manner; and

• Software and Hardware-in-the-loop (HIL) test

platform.

Figure 1. SolarExPert project overview

HNEI’s GridSTART developed, tuned, and calibrated

the detailed electrical model of a very high PV

penetrated distribution feeder on the island of Maui

based on an extensive collection of field measured

data previously captured in the course of U.S.

Department of Energy (DOE) and Office of Naval

Research funded research projects. This high-fidelity

electrical model is used in the testing and tuning of

the open source software of the SGP and advanced

distribution management system functions developed

by UCF.

PROJECT STATUS/RESULTS: In this, the third and

final year of the project, a distribution circuit PV

hosting capacity estimation approach based on

stochastic analysis was developed. The high-fidelity

model of Maui island distribution feeder with

extremely high penetration distributed PV was

utilized to determine the impacts of advanced inverter

control functions on PV hosting capacity.

Uncertainties in the location and size of the future

installed PV systems are considered based on

historical PV data. The PV size sampling result is

shown in Figure 2.

Figure 2. (a) histogram of the 295 installed PV systems and

the estimated probability distribution; (b) histogram of the

sizes of the future PV systems.

The PV hosting capacity analysis focused on feeder

voltage quality, particularly on voltage rise as a

function of installed PV capacity relative to local

load. The hosting capacity improvement with

advanced solar PV inverter Volt/VAR and Volt/Watt

optimization control algorithms are illustrated in

Figure 3. The boundaries determine the minimum and

the maximum hosting capacity.

Figure 3. The PV hosting capacity of the Maui test feeder:

(a) without the voltage control algorithm; (b) with the

advanced Volt/VAR and Volt/Watt control algorithm.

This project was successfully completed in August

2020. Final reports to DOE are being prepared.

Funding Source: U.S. Department of Energy




Sustainable Grid Platform with Enhanced System Layer and Fully Scalable Integration




OBJECTIVE AND SIGNIFICANCE: Wave energy has

enormous potential to address global renewable

energy goals, yet it poses daunting challenges related

to commercializing technologies that must produce

cost-competitive electricity while surviving the

energetic and corrosive marine environment. The

nascent commercial wave energy sector is thus

critically dependent on available test infrastructure to

address these issues. To address this need, the U.S.

Navy established the Wave Energy Test Site (WETS)

in the waters off Marine Corps Base Hawaiʻi (shown

below), the U.S.’ first grid-connected site, completing

the buildout in mid-2015. WETS consists of test

berths at 30m, 60m, and 80m water depths and can

host point absorber and oscillating water column

devices to a peak power of 1 MW. HNEI provides key

research support to this national effort in the form of

environmental monitoring, independent wave energy

conversion (WEC) device performance analysis, and

critical marine logistical support. The results

achieved at WETS will have far reaching impacts in

terms of advancing wave energy globally.

BACKGROUND: Through a cooperative effort

between the Navy and the U.S. Department of Energy

(DOE), WETS hosts companies seeking to test their

pre-commercial WEC devices in an operational

setting. HNEI works with the Navy and DOE to

directly support WEC testing at WETS in three key

ways: 1) environmental impact monitoring – acoustic

signature measurement and protected species

monitoring, 2) independent WEC device performance

analysis – including wave forecasting and

monitoring, power matrix development (power

output versus wave height and period), numerical

hydrodynamic modeling, and a regimen of regular

WEC and mooring inspections, and 3) logistics

support – in the form of past funding to modify a site-

dedicated support vessel for use at WETS, through

local partner Sea Engineering, Inc., assisting WEC

developers with deployment planning, and through

funding to developers for maintenance actions. While

the US DOE funding and cost share from the ESDSF

have been fully expended, the project is continuing

with funding from the Naval Facilities Engineering

Command.

PROJECT STATUS/RESULTS: Since mid-2015, the

major activities have occurred at WETS, with HNEI

in both supporting and leading roles. These are

summarized in the series of figures below.

June 2015 to December 2016: Northwest Energy

Innovations (NWEI) deployed Azura device at 30m

berth.

March 2016 to April 2017: Sound and Sea

Technology deployed Fred. Olsen Lifesaver at 60m

berth. This project was not grid-connected.

Layout of Navy Wave Energy Test Site


Research Support to the U.S. Navy Wave Energy Test Site



February to August 2018: HNEI led second

deployment of Azura, with modifications designed to

improve power performance, including enlarging the

float and adding a heave plate at the base.

October 2018 to March 2019: HNEI led effort to

redeploy Lifesaver, at 30m, with modifications to

moorings and integration of UW sensor package and

subsea charging capability, which drew its power

from the WEC itself. This use of wave energy to

power an offshore sensing suite was an important

national first.

May to June 2019: Led major redesign and

reinstallation effort for the WETS deep berth

moorings. 60m berth reinstalled, with 80m berth

reinstallation planned for spring/summer 2021.

November 2019: Completion of site-dedicated

support vessel Kupaʻa, by research partner Sea

Engineering, Inc. This vessel adds significantly to our

ability to perform various functions at WETS.



At this update, additional activities planned in the

coming year include:

1) Deployment of the C-Power SeaRay WEC. This

will be a stand-alone (not grid-connected)

deployment of a small, 1kW device that will

feed power to a subsea acoustic sensing system

from the company Biosonics.

2) Deployment of the Oscilla Power Triton-C

WEC at the 30m berth.

3) Repairs to the 80m berth.

4) Deployment of the Ocean Energy OE35 WEC

at the 60m berth. The OE35, pictured below, is

a large oscillating water column device currently

on site in Hawaiʻi.

Looking ahead to 2022 and 2023, we expect WEC

deployments from C-Power (a larger device called

StingRay), Northwest Energy Innovations (a much

larger version of Azura), and Aquaharmonics, as well

as ongoing WEC and infrastructure inspections,

maintenance and repairs, acoustic data collection,

wave measurement and forecasting, hydrodynamic

analysis of WEC performance and mooring fatigue,

and other activities in support of DOE, Navy, and

developer test objectives at WETS.

Funding Sources: Naval Facilities Engineering

Command; U.S. Department of Energy; Office of

Naval Research; Energy Systems Development

Special Fund

Contact: Patrick Cross, [email protected]





OBJECTIVE AND SIGNIFICANCE: The project

described here was recently selected for funding by

DOE’s Water Power Technologies Office and builds

on this growing expertise in the nascent field of wave

energy to develop our own WEC concept – from

conception through numerical modeling at two scales

and testing in mainland tank facilities at each scale.

The objective is to mature a WEC concept that can

ultimately produce cost-effective renewably

generated electricity for coastal communities. Its

inherent scalability could support smaller-scale

generation for isolated communities or islands, or

larger-scale devices (likely deployed in arrays) to

generate power to feed into coastal power grids. The

project, called the Hawaiʻi Wave Surge Energy

Converter (HAWSEC), is expected to make

important advances in the emerging wave energy

field and has the potential to mature a technology with

realizable commercial potential in the future – for

Hawaiʻi, the U.S., and beyond.

BACKGROUND: HNEI has been involved in

supporting research and testing objectives at the U.S.

Navy’s Wave Energy Test Site (WETS) off Marine

Corps Base Hawaiʻi since 2010, with funds from both

the U.S. Department of Energy (DOE) and the U.S.

Navy (Naval Facilities Engineering Command –

NAVFAC). This has involved providing

environmental measurements, serving as an

independent third-party assessor of wave energy

converter (WEC) device power performance and

survivability/maintenance issues, and providing key

logistical support to WEC developers and

DOE/Navy. Through this involvement, HNEI has

gained valuable practical experience associated with

real-world deployment and operation of WECs in this

first-of-its-kind in the U.S. grid-connected test site.

Additionally, through numerical modeling of WEC

dynamics and mooring systems in support of WETS

test objectives and WEC developers, HNEI has

accumulated key design insights and numerical

modeling experience related to WEC design.

The HAWSEC concept is based on the oscillating

wave surge energy converter (OWSC), or flap-type,

WEC. Such systems rely on the surge motion of the

waves close to shorelines, where wave direction

becomes more consistent than offshore. The flap

moves back and forth in the waves and drives

hydraulic cylinders to pump water through a hydro

turbine to generate electricity. A rendering of our

conceptual flap is shown below. We will explore both

a high-head/low-flow and a low-head/high-flow

hydraulic system, utilizing the same flap, in the first

half of the project, ultimately settling on an optimized

configuration (with a hydro turbine selected to best

align with the optimized head and flow) before

scaling up for additional testing in the latter stages of

the project.

Figure 1. Artist rendering of the HNEI HAWSEC

system.

HAWSEC development will proceed along the

following broad set of tasks:

1) Numerical modeling of small-scale version,

nominally a 1m x 1m flap, to optimize design;

2) Fabrication and local testing of the small-scale

system – both the hydraulic system and the flap

itself in nearshore waters on Oʻahu;

3) Controlled tank testing of the small-scale system

at Oregon State University’s (OSU) Hinsdale

wave basin;

4) Validation of numerical modeling with test

results from OSU;

5) Numerically scaling up to medium scale,

nominally a 3m x 3m flap, and completing a

buildable design of the HAWSEC at this scale;

6) Undergoing a Go/No-Go decision with DOE;

7) Fabrication of a full medium-scale system,

including flap and hydraulics;

8) Controlled tank testing of the medium-scale

device at the University of Maine’s test flume;

and


The Hawaiʻi Wave Surge Energy Converter (HAWSEC)



9) Validation of medium-scale numerical models

with test data from Maine, and modeling and

performance prediction for a full-scale version

of HAWSEC.

PROJECT STATUS/RESULTS: This three-year project

was initated in August 2020. Significant progress has

been made in the numerical modeling steps for the

smaller-scale device, supporting key design decisions

being made in advance of fabrication of the test article

for this scale. We anticipate readiness for bench

testing of our hydraulic system in March 2021, with

in-ocean testing beginning in May 2021, and OSU

tank testing in the August/September timeframe. This

document will be updated over the course of the

project to include key model results, photos of test

articles, test tank results, and so on.

Funding Source: U.S. Department of Energy, Water

Power Technologies Office; Energy Systems

Development Special Fund

Contact: Patrick Cross, [email protected]






this project was to develop effective methods to

restore the performance loss caused by air

contaminants in proton exchange membrane fuel cell

(PEMFC) systems, especially the losses that cannot

be restored by interrupting the contaminant exposure.

An effective recovery method would slow down the

degradations of membrane electrodes assembly

components and their performances, facilitate the

system meeting with the U.S. DOE technical targets

for PEMFC performance and durability, and

overcome the air pollution challenges to the

applications of PEMFC systems.

BACKGROUND: PEMFC is considered a promising

clean energy technology for transportation and

stationary applications. Currently, Pt-based catalysts

are still extensively applied in PEMFC due to the high

electrochemical activity. Unfortunately, more than

200 airborne pollutants can be introduced into the

PEMFC cathode via the air stream. Air pollution is a

challenge for the PEMFC application.

In past decades, many contaminants were studied

with single cells or stacks using both accelerated and

long-term tests. At HNEI, more than twenty potential

contaminants have been studied in single cell

configurations. Most of these compounds adsorb and

react on Pt surface and compete with oxygen

reduction reaction, a key reaction in PEMFC.

Fortunately, the effects from both unsaturated

hydrocarbon and oxygen-containing hydrocarbon

contaminants, could be mitigated by neat air

operation. However, for sulfur and halogen

compounds, the cell performance suffers a significant

loss and does not recover with the neat air operation.

The contamination also accelerates the permanent

degradation of Pt catalysts and electrolyte membrane.

The contamination mechanisms of those compounds,

i.e. bromomethane, are illustrated in Figure 1. The

contaminants permeate through the thin ionomer film

and break down to adsorbates (BrCH3 to Br-, SO2 to

S and SO42-) on the Pt catalyst surface. The adsorbates

cannot be oxidized or desorbed under normal PEMFC

operating conditions, and accumulate at the catalyst

layer interface. The anions even cannot be removed

by cyclic voltammetry scanning alone due to Donnan

exclusion by the ionomer. The catalyst surface then

loses activities to the fuel cell reactions. For a long-

term operation, the absorption of anions also causes

permanent damages on the MEA, such as Pt

dissolution and particle growth, and ionomer

electrolyte decomposition.

Figure 1. Contamination mechanisms of bromomethane

in PEMFC cathode.

The possible solutions that have been proposed

includes restoring the cell performance by in-situ

potential scanning after the contamination and

eliminating the contaminants with filter before

reaching to the catalyst layer. However, the potential

scanning is not applicable to stacks because the

control of every cathode potential is required for

multiplying electrical connections and equipment

needs. On the other hand, chemical filter typically

only last several months under realistic PEMFC

vehicle operations.

PROJECT STATUS/RESULTS: Under this project, a

performance recovery method has been developed by

HNEI that incorporates a combination of gas purging

and water flushing operations. Specific procedures

are based on a comprehensive understanding on the

contamination mechanisms of the selected air

pollutant. The method, validated using single cells,

was shown to restore the performance losses and

remove the adsorbates and anions after poisoning

with bromomethane, hydrogen chloride, or sulfur

dioxide. Representative results are shown in Figures

2 and 3. The cell performance was restored to 100%,

97% and 99% of its initial value, respectively for

those contaminants.

Hawaiʻi Natural Energy Institute Research Highlights Electrochemical Power Systems

Proton Exchange Membrane Fuel Cell Contamination



Figure 2. (a) Cell performance responses to the

bromomethane contamination and recovery; (b) Cell

polarization curves before poisoning and after recovery.

Figure 3. (a) Cell performance responses to the sulfur

dioxide contamination and recovery; (b) Cell

polarization curves before poisoning and after recovery.

In summary, an effective recovery method has been

developed and demonstrated that yields an almost

complete performance recovery after poisoning with

bromomethane, hydrogen chloride, or sulfur dioxide.

A provisional patent was filed. Collaboration with the

PEMFC stacks manufactures, who are running fuel

cell vehicle demonstrations, is being sought for

further validating the efficiency of the recovery

method for contaminated PEMFC stacks.

Funding Source: Office of Naval Research;

U.S. Department of Energy

Contact: Yunfeng Zhai, [email protected];

Jean St-Pierre, [email protected]






OBJECTIVE AND SIGNIFICANCE: The goals of this

project are evaluation of the performance of anion

exchange membrane fuel cells (AEMFCs) with low

platinum group metal (PGM) content and PGM-free

cathode catalysts under various operating conditions

and advance understanding of effects of membrane

electrode assemblies (MEAs) components on mass

transport and water management.

BACKGROUND: The strongest motivation factor that

has driven interest in AEMFCs technology (Figure 1)

is the possibility of eliminating Pt catalysts from

anode and cathode, since intrinsic catalytic activity

towards oxygen reduction is higher in alkaline media

for PGM-free materials than for Pt-based catalysts.

Figure 1. Schematic representation of AEMFC.

The next logical step will be integration of Pt and

PGM-free catalysts to the AEMFC MEA. However,

well-established technologies of manufacturing of

proton exchange membrane fuel cell (PEMFC)

MEAs cannot be directly transferred into the field of

AEMFCs. The main reasons for getting lower power

output are inability to create properly structured

electrodes with sufficient mass transport, porosity,

electronic conductivity, and catalyst layer (CL)

thickness. The performance can be improved by

advanced design of the electrode layers and adequate

choice of gas diffusion layers (GDLs) for better water

management.

Figure 2. Materials for manufacturing of AEMFC

MEAs: ionomer solution, membrane, GDLs, and

catalyst.

PROJECT STATUS/RESULTS: The project was

initiated in 2020 and the current accomplishments

include:

• The first anion exchange MEA samples with Pt-

based electrodes were assembled.

• A break-in/start-up procedure was established

after discussion with AEM manufactures and

successfully tested.

• Performance of the AEM MEAs was evaluated in

an H2/O2 gas configuration, 150 kPa back

pressure and 80C using polarization curves and

electrochemical impedance spectroscopy (EIS).

• Variation of fuel and oxidant humidification

demonstrated that maximum power density of

750 mW cm-2 was achieved at reduced anode

(50%) and full cathode (100%) gas

humidification.

Future work will include a continuation of

electrochemical studies of AEMFCs using available

methods and techniques.


Contact: Tatyana Reshetenko, [email protected]



Anion Exchange Membrane Fuel Cell




OBJECTIVE AND SIGNIFICANCE: Development of

platinum group metal free (PGM-free) catalyst for

electrochemical oxygen reduction offers a potential to

reduce the production cost of proton exchange

membrane fuel cells (PEMFC). Under this project, we

are developing highly active PGM-free catalysts and

optimizing their incorporation into a fuel cell.

BACKGROUND: Today’s PEMFC commercial energy

generated systems are typically utilizing Pt-based

catalysts for hydrogen oxidation and oxygen

reduction reactions at anode and cathode,

respectively. The substitution of oxygen reduction Pt

catalysts by PGM-free materials delivers not only

lower manufacturing cost (less than or equal to

$3/kW), but also ensures independence from Pt and

other precious metal availability. In addition,

application of PGM-free catalysts at the cathode

provides tolerance to airborne contaminants (NO2,

SO2), which typically seriously affect Pt-based

PEMFC performance.

Figure 1. SEM and HRTEM images of 3rd generation of

Fe-N-C catalysts. The catalyst design resulted in

atomically dispersed Fe-Nx active centers (bright dots at

TEM images).

PGM-free catalysts consist of non-precious transition

metal (Fe, Co, Mn) coordinated by nitrogen inside a

matrix of graphitic carbon and can be inexpensively

manufactured at scale. These catalysts possess high

intrinsic activity for oxygen reduction measured in

electrochemical half-cell configuration. However,

PGM-free electrocatalysts integrated in membrane

electrode assembly (MEA) have underperformed

compared to Pt based fuel cells. The performance can

be improved by synergistic efforts of materials

design, fine tuning of the electrode layer and

comprehensive electrochemical analysis.

This project is a collaboration between industry

(Pajarito Powder LLC, IRD Fuel Cell) and academia

(HNEI) under a U.S. DOE funded project “Active and

durable PGM-free cathodic electrocatalysts for fuel

cell application” (DE-EE0008419). HNEI is

conducting electrochemical evaluation of the PGM-

free PEMFCs using advanced and proven

electrochemical techniques.


• Three generations of PGM-free electrocatalysts

were synthesized using rationally selected

precursors and conditions. Figure 1 shows SEM

images of a catalyst from 3rd generation.

• The electrocatalysts were successfully integrated

into electrode structures applying various

ionomers and additives and using different layer

designs.

• Established testing protocol for PGM-free

PEMFCs which includes measurements of

polarization curves, impedance spectroscopy, and

cyclic voltammetry.

• Evaluated performance of 50 different MEAs.

Achieved Go-no-Go target of 22-27 mA cm-2 at

0.9 V.

Future work will include a continuation of

electrochemical studies of catalysts and electrode

designs using available methods and techniques.

Funding Source: U.S. Department of Energy; Office

of Naval Research; Energy Systems Development

Special Fund

Contact: Tatyana Reshetenko, [email protected]



Active and Durable PGM-Free Catalysts for Fuel Cell Applications






1. 2020, T. Reshetenko, A. Serov, M. Odgaard, G. Randolf, L. Osmierie, A. Kulikovsky, Electron

and proton conductivity of Fe-N-C cathodes for PEM fuel cells: A model-based

electrochemical impedance spectroscopy measurement, Electrochemistry Communications,

Vol. 118, Paper 106795. (Open Access: PDF)

2. 2020, T. Reshetenko, G. Randolf, M. Odgaard, B. Zulevi, A. Serov, A. Kulikovsky, The Effect

of Proton Conductivity of Fe–N–C–Based Cathode on PEM Fuel cell Performance, Journal

of the Electrochemical Society, Vol. 167, Issue 8, Paper 084501. (Open Access: PDF)

3. 2019, T. Reshetenko, A. Serov, A. Kulikovsky, P. Atanassov, Impedance Spectroscopy

Characterization of PEM Fuel Cells with Fe-N-C-Based Cathodes, Journal of the

Electrochemical Society, Vol. 166, Issue 10, pp. F653-660. (Open Access: PDF)

PRESENTATIONS:

1. 2020, T. Reshetenko, G. Randolf, M. Odgaard, B. Zulevi, A. Serov, A. Kulikovsky, Effects of

cathode proton conductivity on PGM-free PEM fuel cell performance, Presented at the ECS

2020-02 Meeting, Honolulu, Hawaiʻi, October 4-9, Abstract 2686.

2. 2019, T. Reshetenko, A. Serov, A. Kulikovsky, P. Atanassov, Comprehensive

Characterization of PGM-Free PEM Fuel Cells Using AC and DC Methods, Presented at the

ECS 2019-02 Meeting, Atlanta, Georgia, October 13-17, Abstract 1617.

3. 2019, A. Serov, G. McCool, H. Romero, S. McKinney, A. Lubers, M. Odgaard, T.V.

Reshetenko, B. Zulevi, PGM-Free Oxygen Reduction Reaction Electrocatalyst: From the

Design to Manufacturing, Presented at the ECS 2019-01 Meeting, Dallas, Texas, May 26-30,

Abstract 1487.

http://dx.doi.org/10.1016/j.elecom.2020.106795



https://www.sciencedirect.com/science/article/pii/S1388248120301466/pdfft?md5=776cfbdadff599a1cddfb362f2070e27&pid=1-s2.0-S1388248120301466-main.pdf

http://dx.doi.org/10.1149/1945-7111/ab8825

http://dx.doi.org/10.1149/1945-7111/ab8825

https://iopscience.iop.org/article/10.1149/1945-7111/ab8825/pdf

http://dx.doi.org/10.1149/2.1431910jes

http://dx.doi.org/10.1149/2.1431910jes

https://iopscience.iop.org/article/10.1149/2.1431910jes/pdf

https://ecs.confex.com/ecs/prime2020/meetingapp.cgi/Paper/142032


http://dx.doi.org/10.1149/MA2019-02/35/1617

http://dx.doi.org/10.1149/MA2019-02/35/1617

http://dx.doi.org/10.1149/MA2019-01/30/1487

http://dx.doi.org/10.1149/MA2019-01/30/1487



OBJECTIVE AND SIGNIFICANCE: Fuel cells offer the

opportunity to significantly increase the flight

duration of electric powered unmanned aerial

vehicles (UAVs). With fuel cell power systems,

increases of 5-10x in flight duration are possible for

the same volume and weight constraints as high

energy lithium batteries. Under this task, HNEI

continued support to the Naval Research

Laboratory’s (NRL) efforts to develop lightweight,

high efficiency fuel cell systems for UAVs.

BACKGROUND: Electric propulsion offers several

advantages over small hydrocarbon powered engines,

i.e. near silent operation, instant starting, increased

reliability, easier power control, reduced thermal

signature, reduced vibration, and no electric

generators. A partnership between HNEI and NRL

was established in 2009 to aid in NRL’s development

of the IonTiger UAV using a fuel cell made by an

outside vendor. HNEI contributed to the program

with testing and evaluation of the fuel cell system and

components as well as determining effects of high

altitude operations on the durability of the fuel cell.

This NRL program resulted in an unofficial world-

record fuel cell powered UAV flight of 26 hours on

compressed hydrogen, and later 48 hours using an

NRL-developed, cryogenic hydrogen storage system.

Figure 1. NRL IonTiger in flight and 550W fuel cell

(insert).

Subsequently, NRL has been developing their own

proprietary fuel cells and systems for UAV

applications. HNEI has supported this effort via

diagnostic testing, evaluation of needs, and design

recommendations.

At the core of HNEI’s capabilities is a configurable

stack test station that can test fuel cell stacks up to

5kW and has the flexibility to adapt to new

technologies. For this work, a helium leak station was

built to evaluate the integrity of new seal designs and

to locate and quantify leak rates. A suite of auxiliary

equipment was also developed to evaluate cell to cell

uniformity leading to design recommendations for

new generations of NRL stack technology. HNEI also

has developed a Hardware-in-the-Loop stack test

station to support balance-of-plant system

development and evaluate the dynamic capabilities of

NRL stack technology. HNEI engineers have

developed numerous stack testing protocols for NRL

including initial break-in, build verification,

durability, and failure diagnostic protocols.

In addition to the testing support, HNEI has also

contributed to the system hardware development. For

example, HNEI designed and reduced to practice a

hydrogen recovery unit for the NRL fuel cell system

to increase hydrogen utilization to greater than 99%

with reduced weight and volume.

PROJECT STATUS/RESULTS: This work has resulted

in publications and one patent application filed for

“Hydrogen Fuel Cell Power Source with Metal

Bipolar Plates”. For additional information refer to

the publication listing on the HNEI website or use the

contact listed below.


Contact: Keith Bethune, [email protected]



Fuel Cell Development for Electric Powered Unmanned Aerial Vehicles





TECHNICAL REPORTS:

1. 2019, K. Bethune, Support to NRL, subsection of Task 2.1 Fuel Cell Testing, in APRISES 14

Final Technical Report, Office of Naval Research Grant Award Number N00014-15-1-0028.

2. 2018, K. Bethune, Support to NRL, subsection of Task 2.1a Fuel Cell Development, in

APRISES 12 Final Technical Report, Office of Naval Research Grant Award Number N00014-

13-1-0463.

3. 2018, K. Bethune, NRL Support, subsection of Task 2.1 Fuel Cell Development, Testing and

Modeling, in APRISES 13 Final Technical Report, Office of Naval Research Grant Award

Number N00014-14-1-0054.


1. 2020, Y. Garsany, C.H. Bancroft, R.W. Atkinson III, K. Bethune, B.D. Gould, K.E. Swider-

Lyons, Effect of GDM Pairing on PEMFC Performance in Flow-Through and Dead-Ended

Anode Mode, Molecules, Vol. 25, Issue 6, Paper 1469. (Open Access: PDF)

2. 2015, B.D. Gould, J.A. Rodgers, M. Schuette, K. Bethune, S. Louis, R. Rocheleau, K. Swider-

Lyons, Performance and Limitations of 3D-Printed Bipolar Plates in Fuel Cells, ECS

Journal of Solid State Science and Technology, Vol. 4, Issue 4, pp. P3063-P3068. (Open Access:

PDF)

PRESENTATIONS:

1. 2020, Y. Garsany, C.H. Bancroft, R.W. Atkinson, K. Bethune, B.D. Gould, K. Swider-Lyons,

Operation of PEMFC Anodes in Dead-Ended Vs. Flow-through Modes, Presented at the

ECS 2020-02 Meeting, Honolulu, Hawaiʻi, October 4-9, Abstract 2212.

2. 2019, R.W. Atkinson, Y. Garsany, K. Bethune, J. St-Pierre, B.D. Gould, K. Swider-Lyons,

Pairing Asymmetric Gas Diffusion Media for High-Power Fuel Cell Operation, Presented at

the ECS 2019-02 Meeting, Atlanta, Georgia, October 13-17, Abstract 1428.

3. 2019, Y. Garsany, R.W. Atkinson, K. Bethune, J. St-Pierre, B.D. Gould, K. Swider-Lyons,

Cathode Catalyst Layer Design with Graded Porous Structure for Proton Exchange

Membrane Fuel Cells, Presented at the ECS 2019-02 Meeting, Atlanta, Georgia, October 13-

17, Abstract 1423.








http://dx.doi.org/10.3390/molecules25061469

http://dx.doi.org/10.3390/molecules25061469


http://dx.doi.org/10.1149/2.0091504jss

http://jss.ecsdl.org/content/4/4/P3063.full.pdf+html


http://dx.doi.org/10.1149/MA2019-02/32/1428

http://dx.doi.org/10.1149/MA2019-02/32/1423

http://dx.doi.org/10.1149/MA2019-02/32/1423




this project is to develop transition metal carbide

catalysts for electrochemical applications. These

carbide catalysts have the potential to improve the

performance of a variety of electrochemical devices

including fuel cells, water electrolyzers, and

vanadium redox flow batteries.

BACKGROUND: The commercial application of a

number of electrochemical technologies would

benefit from the availability of low cost, efficient,

and durable catalysts. Pt-group metals-based catalysts

are used in most commercially available fuel cells and

water electrolyzers. Unfortunately, they have the

shortcomings of high cost, low earth abundance, and

limited lifetime. Vanadium redox flow batteries

(VRFBs) have recently attracted considerable

attention for large-scale energy storage. Graphite or

carbon materials have been the most common

catalysts for VRFBs. However, they often show

limited activity and reversibility. Transition metal

carbides are regarded as attractive candidates because

they possess an electronic structure similar to Pt

which promotes high activities, good electronic

conductivity, low cost, high abundance, and

outstanding thermal and chemical stabilities. The

catalytic properties of carbide catalysts strongly

depend on their surface structure and composition,

which are closely associated with their synthesis

methods.

PROJECT STATUS/RESULTS: The research team at

HNEI is currently focused on the synthesis of carbide

catalysts for VRFBs. Rather than applying the

conventional carbide synthesis method by

carburization of metal precursor with hydrogen as

reducing agent and carbonaceous gas (e.g. CH4) as

carbon source, this work is exploring in-situ

carburization of metal precursor with carbon material

as carbon source and support without using any

gaseous carbon source (Figure 1). This simple

systhesis method avoids the use of environmentally

unfriendly and flammable gases which are potential

safety hazards in the operation. In addition, the use of

carbon material as carbon source and support favors

the formation of nano-sized carbides that are expected

to possess a large specific surface area. Vanadium

carbide supported on Vulcan XC72 (VCXC72) shows

uniform distribution (Figure 2) and smaller particle

size (~32nm) than on graphite (VCgraphite, ~44nm) and

carbon obtained from the carbonization of coconut

husk (VCcoconut, ~41nm). Vanadium carbides exhibit

significantly better catalytic activities and enhanced

reversibility toward the negative electrode reactions

for VRFBs than graphite which is the incumbent

catalyst for VRFBs (Figure 3). The use of vanadium

carbide catalysts for VRFBs has not yet been reported

in the literature.

Figure 1. Schematic representation of the synthesis process

for transition metal carbides.

Figure 2. Transmission electron microscopy image of

vanadium carbide on Vulcan XC72.

Figure 3. Cyclic voltammograms on vanadium carbides at

5mV s−1 in N2 saturated 3M H2SO4+1M (V2++V3+) at 25oC.


Contact: Jing Qi, [email protected]; Jean St-Pierre,

[email protected]


carburization

Carbon source Metal precursor TMC

Ar

VCXC72-acid

-0.5 -0.4 -0.3 -0.2 -0.1

-40

-30

-20

-10

0

10

VCx-072219(3M H2SO4)

VCx-072519(3M H2SO4)

VCx-122319(3M H2SO4)

graphite

V3+ + e- → V2+

V2+ - e- → V3+

VCgraphite

VCcoconut

VCXC72

graphite1M V(II+III)+3M H2SO4, N2, 5mV/s, 25oC

I (m

A c

m-2

)

E (V vs. RHE)


Transition Metal Carbide Catalysts for Electrochemical Applications






this work is to better understand the degradation of

batteries in grid deployed systems. The knowledge

gained in this project will inform best practices to

improve durability and safety of large batteries

deployed on the electric grid.

BACKGROUND: Battery Energy Storage Systems

(BESS) show promise in mitigating many of the

effects of high penetration of variable renewable

generation. HNEI has initiated an integrated research,

testing, and evaluation program to assess the benefits

and durability of grid-scale BESS for various

ancillary service applications. BESS were deployed at

3 sites. The first one was deployed in December 2012

on the Big Island of Hawaiʻi. The other two were

deployed on Molokaʻi and Oʻahu in 2016 (Appendix

B1). Usage was closely monitored and maintenance

cycles using protocols recommended by the

manufacturer, as well as custom HNEI protocols,

were applied.

PROJECT STATUS/RESULTS: Usage from the BESS

was carefully analyzed to facilitate laboratory testing

of individual cells representative of actual operating

conditions.

All cells used in the demonstrations and laboratory

testing were Li-ion titanate from Altairnano. Close to

100 cells were tested in the lab to monitor aging

patterns, reproduce the aging observed in real life, and

accelerate the degradation.

This project showed that, because of the lower

voltages, these cells are far less sensitive to

degradation induced by calendar aging and high state

of charges than traditional Li-ion batteries. Moreover,

their capacity fading pace is also slower. Based on our

results, we are projecting that accelerated

degradation, a typical occurrence in traditional

lithium ion batteries, remains of concern under

certain conditions, notably if the cells are kept

consistently above 35oC (Figure 1). Research

conducted for this project is completed in the PakaLi

Battery Laboratory.

This is an ongoing project, which has led to 10

publications so far including: “Battery Energy

Storage System battery durability and reliability

under electric utility grid operations: Analysis of 3

years of real usage” in the Journal of Power Sources,

Vol. 338, pp. 65-73 and “Battery durability and

reliability under electric utility grid operations:

Representative usage aging and calendar aging” in

the Journal of Energy Storage, Vol. 18, pp. 185-195.


Contact: Matthieu Dubarry, [email protected];




Battery Energy Storage Systems Durability and Reliability

https://www.hnei.hawaii.edu/facilities/pakali-battery-lab

https://www.hnei.hawaii.edu/facilities/pakali-battery-lab

http://dx.doi.org/10.1016/j.jpowsour.2016.11.034




https://dx.doi.org/10.1016/j.est.2018.04.004








this work was to characterize the impact of fast

charging and grid-vehicle interactions on the

performance and durability of Li-ion batteries in

electric vehicles. The knowledge gained in this

project inform best practices to help implement

successful electric vehicle fast charging, vehicle-to-

grid (V2G), and grid-to-vehicle (G2V) programs.

BACKGROUND: Electrification of automobiles and

fossil-fuel displacement by renewable energy sources

are crucial to combat climate change. The successful

adoption of these clean energy technologies could

benefit from integration strategies such as fast

charging and the sourcing/sinking energy to/from the

electric grid known as V2G and G2V, respectively.

Understanding and mitigating battery degradation is

key to improving the durability of electric vehicles

and the reliability of power grids. Battery degradation

is path dependent; this means that not only the

degradation pace is affected by usage but also the type

of degradation the batteries experience. Lithium-ion

batteries are known to degrade slowly at first before a

rapid acceleration of which starting time will depend

on the degradation mechanisms.

PROJECT STATUS/RESULTS: Our study showed that

a simplistic approach to V2G, namely that an EV is

discharged at constant power for 1h without

consideration of battery degradation, is not

economically viable because of the impact additional

V2G cycling has on battery life. However, we showed

that if the batteries are to be used for frequency

regulation, there is a much lesser impact.

It must be noted that, because of path dependence,

different usages might lead to different results and

thus that our results should not be generalized. This

was proved further through the fast charging side of

this project where batteries were shown to have 4x

shorter life even though they were used less

aggressively than other similar cells.

Overall, our work showed that, with good battery

prognostic models and further advances in

understanding the causes, mechanisms and impacts of

battery degradation, a smart control algorithm could

take all these aspects in consideration and make V2G

and fast charging a reality. Research conducted for

this project is completed in the PakaLi Battery

Laboratory.

This project is ongoing. This project led to 10

publications so far, including: “The viability of

vehicle-to-grid operations from a battery

technology and policy perspective” in Energy

Policy, Vol. 113, pp. 342-347 and “Durability and

Reliability of Electric Vehicle Batteries Under

Electric Utility Grid Operations: Bidirectional

Charging Impact Analysis” in the Journal of Power

Sources, Vol. 358, pp. 39-49.


Contact: Matthieu Dubarry, [email protected]



Path Dependence of Battery Degradation, EV Batteries for Grid Support

http://www.hnei.hawaii.edu/facilities/pakali-battery-lab/


http://dx.doi.org/10.1016/j.enpol.2017.11.015



https://dx.doi.org/10.1016/j.jpowsour.2017.05.015







OBJECTIVE AND SIGNIFICANCE: Development of

tools, protocols, and new approaches to improve

batteries diagnosis and prognosis via non-invasive in-

operando techniques.

BACKGROUND: Battery diagnosis and prognosis is a

difficult task. Lithium-ion batteries (LiB) are much

more complex than traditional batteries and their

degradation is path dependent as different usages

(current, temperature, SOC range, SOC window…,

etc.) will lead to different degradation. Also, large

battery packs are comprised of thousands of cells.

This precludes the practical use of complex models or

a multitude of sensors for each cell.

Traditionally, battery diagnosis is handled via two

opposite approaches. The academic route aims for

maximum accuracy and achieves it by inputting a lot

of resources. The second route -- the one usually used

on deployed systems -- is opposite and uses as little

resources as possible and must not be destructive. As

a result, it is ineffective in predicting the true state of

health of the cells.

This assessment of state of the art led HNEI to define

and develop a third industry-compatible intermediate

route to reach an accurate diagnosis with a cost-

effective and non-destructive method, using only

sensors already available in battery packs while

requiring limiting computing power.

Machine learning and artificial intelligence are

starting to play a crucial role to diagnose and

prognose batteries. However, their accuracy is limited

by the little to no training data available to validate

algorithms. To solve this issue, HNEI used its

experience to develop the first synthetic training

datasets using computer-generated voltage curves.

Research conducted for this project is completed in

the PakaLi Battery Laboratory.

PROJECT STATUS/RESULTS: This project is

currently ongoing. A full suite of software and models

were developed. The main model has been licensed

by more than 65 organizations worldwide. This work

led to 35 publications and one patent.

Latest publication: 2020, M. Dubarry, D. Beck, Big

data training data for artificial intelligence-based

Li-ion diagnosis and prognosis, Journal of Power

Sources, Vol. 479, Paper 228806.

Funding Source: Office of Naval Research; SAFT




Battery Diagnosis and Prognosis

https://www.hnei.hawaii.edu/facilities/pakali-battery-lab/

http://dx.doi.org/10.1016/j.jpowsour.2020.228806






OBJECTIVE AND SIGNIFICANCE: Optimization of

battery electrodes to improve performance by tuning

architecture.

BACKGROUND: Advanced energy conversion

devices typically rely on composites electrodes made

of several materials interacting with one another.

Understanding their individual and combined impact

on degradation is essential in the pursuit of the best

possible performance and safety. In this project we

use Designs of Experiments (DoE) as a statistical tool

to optimize formulations and to investigate the

importance of process parameters while minimizing

resources.

Defining new approaches to minimize experiments

and time to reach an optimal battery electrode

composition is highly beneficial to the field. To this

end, we used the DoE approach and a mixture design

was applied for the first time in open literature to

electrode formulation. Consequently, the relationship

between electrode composition, microstructure and

electrochemical performance was uncovered on

known and novel materials.

In this project, the DoE approach is applied to two

types of electrodes: high power electrodes for lithium

batteries (ORN funded, in collaboration with the

University of Montreal) and sodium intercalation

electrodes (DOI funded, in collaboration with Trevi

Systems and the University of Nantes) to investigate

the feasibility of desalination batteries. Research

conducted for this project is completed in the PakaLi

Battery Laboratory.

PROJECT STATUS/RESULTS: This is an ongoing

project. A high power battery system was optimized

in collaboration with the University of Montreal. This

work has led to the two following publications listed

so far. Current work is focused on the desalination

with the screening of different active materials. We

are currently running experiments with materials able

to intercalate and release sodium ions in real sea water

more than 800 times.

2020, O. Rynne, M. Dubarry, C. Molson, E. Nicolas,

D. Lepage, A. Prébé, D. Aymé-Perrot, D. Rochefort,

M. Dollé, Exploiting Materials to Their Full

Potential, a Li-Ion Battery Electrode Formulation

Optimization Study, ACS Applied Energy

Materials, Vol. 3, Issue 3, pp. 2935-2948.

2019, O. Rynne, M. Dubarry, C. Molson, D. Lepage,

A. Prébé, D. Aymé-Perrot, D. Rochefort, M. Dollé,

Designs of Experiments for Beginners—A Quick

Start Guide for Application to Electrode

Formulation, Batteries, Vol. 5, Issue 4, Paper 72.

(Open Access: PDF)

Funding Source: Office of Naval Research; U.S.

Department of Interior; Trevi Systems

Collaboration: University of Montreal (Canada),

University of Nantes (France)




Battery Electrode Optimization



http://dx.doi.org/10.1021/acsaem.0c00015



https://dx.doi.org/10.3390/batteries5040072








this research activity is to develop a high power and

energy density durable and safe vanadium flow

battery (VFB) with a high concentration of vanadium

electrolytes. The proposed research has the potential

to double the energy density of vanadium

electrolytes, and significantly improve the negative

electrode performance. If successful, this work would

facilitate the VFB system meeting with the U.S. DOE

technical targets for the durable and low-cost

electricity’s energy storage applications.

BACKGROUND: A flow battery is an electrochemical

device that comprises a cell stack to reversibly

convert the chemical energy of electrolytes to

electricity, and external tanks to store the electrolytes

containing redox-active species. The sizes of stack

and tanks determine the power (kW) and the energy

capacity (kWh) independently. The separation of

energy storage from the electrochemical conversion

unit enables the power and the energy capacity to be

independently scaled up for the storages from a few

hours to days, depending on the application. For large

scale applications, flow batteries also have several

key advantages compared to the traditional

rechargeable (e.g. Li-ion and lead-acid) batteries,

including longer operational lifetimes with deep

discharge capabilities, simplified manufacturing, and

improved safety characteristics.

To date, VFB is technically the most advanced system

of the under-developing flow batteries. Due to it using

only one element (vanadium) in both tanks, it

overcomes cross-contamination degradation, a

significant issue with other flow batteries that use

more than one active element. The vanadium ions

with oxidation states of 2+/3+ and 4+/5+ are used as

active species in the negative and positive electrolytes

respectively. The energy density of VFBs depend on

the concentration of vanadium: the higher

concentration, the higher energy density. The

maximum concentration of electrolytes depends on

the solubility of VOSO4, a starting electrolyte, and the

stability of vanadium species. The solubility of V2+,

V3+ and VO2+(4+) decreases with increase of the

sulfate concentration due to the common-ion effect;

but the stability and solubility of VO2+(5+) increase

with increase of the acid concentration. Therefore, the

concentration of sulfuric acid and vanadium is usually

controlled at 2-4 M and 1-2 M, respectively, which is

relatively low for the energy storage application. In

addition, VFBs usually require expensive polymer

membranes due to the highly acidic and oxidative

environment, which lead to high system costs. The

low energy densities, along with high capital cost,

make it difficult for the current VFBs to meet the

performance and economic requirements for broad

market penetration. To reduce VFBs’ cost, a number

of research has been conducted, which aims to

improve the vanadium electrolyte energy density and

the system performance by increasing vanadium

concentration.

Since late 2019, HNEI has conducted VFB research

activities to improve the VFB performance and

energy density. One of the efforts is diminishing the

acid concentration in V2+, V3+, and VO2+ electrolytes

to increase the vanadium concentration. A novel

electrochemical procedure has been developed to

prepare a low acid and high vanadium (V3+)

concentration negative electrolytes. The obtained

negative electrolyte contains a maximum 5 M

vanadium with ~0.1 M H+, and the positive

electrolyte maximizes to ~3 M vanadium. These

increased vanadium concentrations in negative and

positive electrolytes imply a potential double

improvement of the energy density of vanadium

electrolytes. The prepared electrolytes were used to

validate the charge-discharge feasibility in a single

cell with an anion exchange membrane (AEM) in the

VFB instead of the conventional proton exchange

membrane. The key features of a VFB cell with AEM

are illustrated in Figure 1.

Figure 1. The features of a VFB cell with AEMs.


Vanadium Flow Battery with High Concentration Electrolytes



During the charge-discharge processes, vanadium

redox reactions take place in negative and positive

electrolyte, and the bisulfate ions transport through

AEM to form the internal electric circuit.

Simultaneously, the sulfuric acid concentration

variation also maintains the stability of the positive

electrolyte. As shown in Figure 2, a single cell

with 3 M vanadium electrolytes in both sides

successfully demonstrates a good charge-discharge

performance. Both positive and negative electrodes

show low overpotentials. However, the low ionic

conductivity of the AEM and the negative

electrolytes, as well the high proton permeability of

the AEM result in large ohmic losses and a low

energy efficiency. Furthermore, due to the poor AEM

chemical and mechanical properties, the electrolytes

leakage caused the operation failure during the

second discharging.

Figure 2. Charge-discharge cycles of VFB with an AEM

and 3 M electrolytes in both side.

PROJECT STATUS/RESULTS: An electrochemical

procedure has been developed to prepare a low acid

(H+ low to 0.1 M) and high vanadium concentration

(V up to 5 M) negative electrolytes. The acid

concentration decreases by a factor of more than 30

and the vanadium concentration doubled compared to

the state of the art. Single cells operated with the high

concentration vanadium electrolytes were evaluated

with different AEMs and demonstrated good

performance and low overpotentials for both positive

and negative electrodes. Challenges were identified

as the low chemical and mechanical stability and the

high proton permeability of the AEMs, and the low

ionic conductivity of the AEMs and the negative

electrolytes.


Contact: Yunfeng Zhai, [email protected]

Last updated: October 2020





this research is to develop high-throughput ink-based

fabrication techniques for light-weight thin film

photovoltaics (PV). This approach has the potential to

significantly reduce manufacturing costs and enable

PV integration on non-conventional substrates, such

as polyamides or woven fabrics.

BACKGROUND: Crystalline silicon has been leading

the PV market for over 20 years. These panels, found

on roof-tops and in centralized production plants, are

easily recognizable by their architecture, with

interconnected wafer-like solar cells laminated under

a flat sheet of glass. Although well-suited for

stationary electrical production, the mechanical

rigidity and weight of silicon PV modules become a

burden for mobile applications, where portability is

far more critical than raw performance. To this

regard, R&D efforts have been recently focused on

methods to integrate ultra-light and flexible thin film

solar materials onto lightweight/flexible substrates,

including plastics (polyamides) and fabrics. Such

devices can generate enough electricity to power

small electronic devices (phones and electronic

tablets for civilians) and sensors (healthcare diagnosis

instruments for military personnel), providing a

reliable source of energy for a variety of military and

commercial applications.

PROJECT STATUS/RESULTS: With support from the

Office of Naval Research, the research team at the

HNEI/Thin Films Laboratory is developing a unique

method to print thin film-based PV. Rather than

relying on conventional vacuum-based deposition

tools, which are costly to operate and maintain, this

technique uses liquid molecular inks which already

contain all the chemical elements necessary for the

synthesis of the solar absorber. These inks can be

easily printed and cured to form thin film solar

absorbers. Our project is currently focused on an

Earth-abundant multi-compound alloy (Cu2ZnSnSe4,

CZTSe), a material which meets the mechanical and

weight requirements for light weight flexible PV.

Results of this work show that high-quality CZTSe

solar absorbers can be achieved with this printing

technology. Solar cells with power conversion

efficiency over 7% have been fabricated. However,

CZTSe has the potential to achieve much higher

efficiency, up to 20%.

Current work focuses in development of innovative

techniques to passivate defects in CZTSe solar

absorbers and improve their conversion efficiency

(primarily increase cells output voltage). This

technique is also being evaluated to synthesize other

solar absorbers with promising properties for PV

applications, including Cu(In,Ga)Se2 and

Cu(In,Al,B)Se2.


Contact: Nicolas Gaillard, [email protected]


Hawaiʻi Natural Energy Institute Research Highlights Advanced Materials

Printable Photovoltaics

+

+

PRINT & HEAT Cu2ZnSnSe4

PV

Molecular ink

(stable over 12 months)

Cross-section of a printed

CZTSe solar absorber

Current vs. voltage of a printed

CZTSe solar cell

Chlorides

Thiourea

Methanol





this project is to synthesize and characterize novel

modified magnesium boride, MgB2, materials with

improved hydrogen cycling kinetics and hydrogen

storage capacities and demonstrate their capability to

meet the U.S. Department of Energy (DOE) hydrogen

storage targets. If successful, the solid-state modified

MgB2 materials would be safer and cheaper than the

high pressure compressed H2 (700 bar) or liquid H2

alternative onboard vehicle hydrogen storage systems

on the market.

BACKGROUND: Magnesium borohydride, Mg(BH4)2,

is one of the few materials that has a demonstrated

gravimetric hydrogen storage capacity greater than 11

wt% and thus a demonstrated potential to be utilized

in a hydrogen storage system meeting U.S. DOE

hydrogen storage targets. However, due to extremely

very slow kinetics, cycling between Mg(BH4)2 and

MgB2, has been accomplished only at high

temperature (~400 °C) and under high charging

pressure (~900 bar). More recently, tetrahydrofuran

(THF) complexed to Mg(BH4)2 has been shown to

vastly improve the kinetics of dehydrogenation,

enabling the rapid release of H2 at < 200 °C to give

Mg(B10H10) with high selectivity. However, these

types of materials have much lower hydrogen cycling

capacities. This project is focused on development of

modified MgB2 by either extending the

dehydrogenation of magnesium borane etherates to

MgB2 or by direct syntheses of the modified MgB2 in

presence of additives. The immediate goal of the

third-year project period is to show hydrogenation at

temperatures and pressures below 300 bar and 250

°C. This will be a significant improvement over the

pre-project state of art (900 bar and 400 oC), as well

as our previous year project achievement of 400 bar

and 300 oC.

This HNEI-led project is a collaborative effort

between UH (HNEI and the Department of

Chemistry) and the DOE-HyMARC Consortium

including Sandia National Laboratory, Lawrence

Livermore National Laboratory, and National

Renewable Energy Laboratory.

PROJECT STATUS/RESULTS: This research effort is

focused on the direct syntheses and analyses of

modified MgB2* formed from pure MgB2 or its

precursors (Figure 1), while the Department of

Chemistry’s effort is focused on forming modified

MgB2 through the dehydrogenation of magnesium

boranes and magnesium borohydride. The project is

guided by computational calculations from Lawrence

Livermore National Laboratory (Figure 2). The

molecular dynamic simulations suggest that the

selected additives can modify the MgB2 structure

rendering it susceptible to hydrogenation at moderate

conditions compared to pure MgB2.

Figure 2. Molecular Dynamic Simulations showing

MgB2 basal plane structure evolution in presence of

THF additive. THF induces defect formation on B

sheets which may facilitate borohydride formation

during hydrogenation.

To date, significant progress has been made towards

improving the hydrogen storage properties of

MgB2/Mg(BH4)2 system (Figure 3). The bulk MgB2

hydrogenation pressure has been reduced from 900

bar to 400 bar and temperatures from 400 °C to 300

°C, while maintaining the MgB2 to Mg(BH4)2

conversion of greater than 75%. Recent results

indicate that MgB2, modified with a unique

combination of additives can be hydrogenated to

Mg(BH4)2 at the moderate conditions of 160 bar and

250 °C. However, the hydrogenation is still limited to

the surface of the material with minimum hydrogen

uptake into the bulk of the material.


Magnesium Boride Etherates for Hydrogen Storage

Figure 1.



Hence, our current research effort is towards

improving the hydrogen uptake into the bulk of the

material, at these desirable lower pressure and lower

temperature conditions. A variety of characterizations

being performed on the hydrogenated MgB2 materials

to determine their hydrogen storage properties are

shown in Figure 4. We have utilized temperature

programmed desorption coupled to mass

spectroscopy (TPD) and thermogravimetric analyses

(TGA) to confirm the hydrogen gravimetric density

and purity of the hydrogen released from the modified

materials. Nuclear magnetic resonance (NMR) and

infrared spectroscopy (FTIR) are being utilized to

directly confirm the formation of Mg(BH4)2 from

Figure 2. TPD analyses of hydrogen evolution from a

MgB2 -10 mol% graphene nanoplatelets sample before

(PRE) and after (POST) hydrogenation at 400 bar and

300 oC.

-6

-4

-2

0

2

Hea

t F

low

(W

/g)

92

94

96

98

100

102

Weig

ht (%

)

50 150 250 350 450 550Temperature (°C)

Figure 2. Typical temperature programmed desorption

(TPD) data of materials hydrogenated at 700 bar and 300

°C showing hydrogen release for three different modified

samples (A-C).

Figure 2. Typical temperature programmed desorption

(TPD) data of materials hydrogenated at 700 bar and 300

°C showing hydrogen release for three different modified

samples (A-C).

(a) TGA-DSC analyses of a MgB2 modified with 10 mol%

graphene nanoplatelets.

(b) Typical TPD data of materials showing hydrogen release

for three different modified samples (A-C).

(c) 11B Solid State NMR of a modified material confirming

conversion of MgB2 to Mg(BH4)2.

(d) FT-ATR confirming Mg(BH4)2 syntheses in modified

samples, B-H peaks: 2200-2400 cm-1 and 1200-1400 cm-1

region. Figure 4. Typical characterizations of modified MgB2 materials hydrogenated at ≤700 bar and ≤300 °C; (a) TGA-DSC,

(b) TPD (c) NMR and (d) FTIR.

Temperature (°C)

Figure 3. Progression of project efforts towards improving hydrogen storage properties of MgB2/Mg(BH4)2 system.

ModifiedPure

➢ Lower hydrogenation temperature.

➢ Lower hydrogenation pressure.

➢ Increase hydrogen sorption rates.

Period 1

700 bar

300 oC

≥ 900 bar

~ 400 oC

Period 2

400 bar

300 oC

Period 3

≤ 300 bar

≤ 250 oC

Bulk MgB2 hydrogenation

State of art Current Project



the MgB2 after hydrogenation process. The TPD

analyses indicates only trace amounts of gas

impurities during dehydrogenation of the materials.

Table 1 provides a summary of the progression of

gravimetric hydrogen densities and percent

conversion of the modified MgB2 materials from the

inception of the project.

The continuous improvement of the hydrogenation

conditions of MgB2 from the state of art 900 bar and

400 °C to now 160 bar and 250 °C shows the

plausibility of continuously improving the

hydrogenation kinetics of the MgB2 to Mg(BH4)2, to

conditions relevant for onboard hydrogen storage.

A peer reviewed, journal cover article on discovery of

additives for enhancing MgB2 hydrogenation kinetics

has resulted from this work.

Funding Source: U.S. Department of Energy,

EERE; Energy Systems Development Special Fund

Contact: Godwin Severa, [email protected]


Table 1. Our research shows plausibility of continuously improving the MgB2 hydrogenation to Mg(BH4)2, to fuel cell

technology relevant pressures and temperatures.


TECHNICAL REPORTS:

1. 2020, HyMARC Seedling: Development of Magnesium Boride Etherates as Hydrogen Storage

Materials, G. Severa, C. Jensen, C. Sugai, S. Kim, 2019 DOE Hydrogen and Fuel Cells Program, Annual

Progress Report to the U.S. Department of Energy for Contract Number DE-EE0007654.








1. 2019, C. Sugai, S. Kim, G. Severa, J. L. White, N. Leick, M. B. Martinez, T. Gennett, V. Stavila, and C.

Jensen, Kinetic Enhancement of Direct Hydrogenation of MgB2 to Mg(BH4)2 upon Mechanical

Milling with THF, MgH2, and/or Mg, ChemPhysChem, Vol. 20, pp. 1-5.


https://www.hydrogen.energy.gov/pdfs/progress19/h2f_st138_severa_2019.pdf

https://www.hydrogen.energy.gov/pdfs/progress19/h2f_st138_severa_2019.pdf

https://www.hydrogen.energy.gov/pdfs/progress18/h2f_severa_2018.pdf

https://www.hydrogen.energy.gov/pdfs/progress18/h2f_severa_2018.pdf

https://www.hydrogen.energy.gov/pdfs/progress17/iv_c_11_severa_2017.pdf

https://www.hydrogen.energy.gov/pdfs/progress17/iv_c_11_severa_2017.pdf

http://dx.doi.org/10.1002/cphc.201801187

http://dx.doi.org/10.1002/cphc.201801187




this project is to obtain key information that can be

used for the development of a comprehensive, multi-

scale computational model of reversible

hydrogenation of magnesium boride, MgB2 to

magnesium borohydride, Mg(BH4)2. If successful, the

project will significantly accelerate the discovery of

boride materials for practical hydrogen storage

applications. The project provides excellent training

on state-of-the-art instrumentation to the participating

UH graduate students, postdoc fellows, and early

career scientists and enhances research

competitiveness at UH by strengthening ties with

U.S. national laboratories.

BACKGROUND: The magnesium boride/magnesium

borohydride (MgB2/Mg(BH4)2) material system is

one of the few cyclable materials that has a

demonstrated gravimetric hydrogen storage capacity

greater than 11 wt% and hence has a potential to be

utilized in a hydrogen storage system that meets U.S.

DOE hydrogen storage targets. This project works

towards obtaining experimental information of 1) the

bulk, nano-scale, and meso-scale structural changes

occurring at elevated pressure following mechano-

chemical modification of MgB2; 2) the reaction

pathway of the reversible hydrogenation of MgB2 to

Mg(BH4)2; 3) the effect of elevated pressure and

mechano-chemical modification on the chemical

reaction pathways; 4) the interactions at solid-gas

interfaces and particle surfaces; and 5) the kinetics

and thermodynamic parameters associated with each

step of the hydrogenation reaction pathway. The

fundamental experimental information derived from

the project will be used for the development of a

comprehensive, multi-scale computational model of

reversible hydrogenation of MgB2 to Mg(BH4)2 at the

Lawrence Livermore National Laboratory.

This EPSCoR project is a collaborative effort

between UH (HNEI, Mechanical Engineering (ME),

Department of Chemistry, and Hawaiʻi Institute of

Geophysics (HIGP)) and the National Renewable

Energy Laboratory (NREL). The HNEI effort is

focused on Vibrational and Raman Spectroscopy

studies of modified MgB2, as well as Calorimetry

studies of the initial stages of hydrogen uptake.

PROJECT STATUS/RESULTS: We have prepared ball

milled samples of pure magnesium boride and MgB2

containing various modifiers, and performed in-situ

hydrogenation studies of the samples using Diffuse

Reflectance Infrared Fourier Transform Spectroscopy

(DRIFTS) in collaboration NREL. The purpose of the

DRIFTS studies is to provide insights into the initial

steps involved in the hydrogenation of modified

MgB2 materials. We are also probing the presence of

B-H, Mg-H, and unanticipated bonding in the

hydrogenated materials. The DRIFTS spectra of the

modified MgB2 samples indicate two unique

overlapping vibrational peaks in the 1200-1400 cm-1

region, that increase in intensity with hydrogenation

temperature (Figure 1). These new broad peaks can

be observed to varying degrees in the modified

samples between 180-350 °C, hence are attributed to

hydrogen interaction with the MgB2. Comparison of

the relative intensities of the 1200-1400 cm-1 features

suggest that the anthracene and Mg-THF additives

lead to the highest surface hydrogen uptake at these

low hydrogen pressure conditions. We are currently

ascertaining whether the vibrational peaks observed

at 1200-1400 cm-1 are due to B-H-B bond formation

during the initial stages of hydrogen uptake.

Furthermore, Raman studies are underway to assist in

correlating the changes in boron-boron bonding

occurring following mechano-chemical modification

of MgB2, to the extent of hydrogen uptake.

Figure 1. Summary DRIFTS spectra of modified MgB2

materials in the B-H bend region showing presence of

new peak at 1200-1400 cm-1 during hydrogenation.

Funding Source: U.S. Department of Energy,

EPSCoR




Develop Advanced Magnesium Boride Hydrogen Storage Materials





this project is the design, synthesis, and

characterization of novel, reversible high-

performance acidic gas (SOx, NOx, and H2S)

contaminant absorbent materials. The materials under

development will enable fuel cell vehicles to be

efficiently operated under harsh atmospheric air

environments. If successful, sorbents under

development will assist the fuel cell filter industry,

and reduce environmental contamination from

hazardous absorbent waste.

BACKGROUND: Current state-of-the-art gas

purification technologies for acidic gas capture based

on metal oxides and hydroxides do not meet all of the

performance requirements of today’s gas purification

in terms of sorption: kinetics, capacities, selectivity,

and reversibility. This leads to large volumes of

polluted absorbent waste. This situation can be

expected to worsen in the future with the increased

use of fuel cell vehicles that require abundant

efficiently purified air as an oxygen source.

The sorbent classes under development include ionic

liquids, metallo ionic liquids, and MOF-activated

carbons. The sorbent material properties are

optimized through a combination of careful selection

of reactants and modification of the sorbent cation

and anion groups. For instance, metallo ionic liquids

with a high content of the small, highly charged

acetate and croconate groups, and transition metal

ions with expandable coordinative environments are

being designed, synthesized, and characterized.

Nano confinement of the absorbents in highly porous

materials is being performed in order to increase

acidic gas-sorbent interactions and hence gas sorption

performance. Nano confinement is especially critical

for ionic liquids absorbents since they have high

viscosity, which limits gas diffusion distances into the

bulk of the material. We have physically deposited

thin films of 1-ethyl-3-methyl imidazolium acetate

ionic liquid onto activated carbon that remain intact

during exposure to SO2 and/or NO2 contaminated air

streams. The sorbents being developed also have

relevance in other applications requiring acidic gas

(SOx, NOx, and H2S) contaminant mitigation,

including flue gas cleaning and natural gas

purification.

PROJECT STATUS/RESULTS: Our work has shown

that nano confined acetate based ionic liquids have

high potential for SO2 capture, with higher

breakthrough capacities and times observed with the

1-ethyl-3-methylimidazolium acetate, compared to

pure activated carbon and activated carbon supported

potassium hydroxide sorbents (Figure 1, below).

Furthermore, we have recently prepared novel acetate

based metallo ionic liquids and ionic salts containing

Mn and Fe with potential for acid gas capture at

comparatively low cost compared to the pure ionic

liquids. We have obtained the crystal structures of the

anhydrous and hydrated M4(OAc)10[C2mim]2 (M=Mn

or Fe). Preliminary gas sorption analyses on the

Fe4(OAc)10[C2mim]2 sorbent indicate plausibility for

reversible acid gas capture (Figure 2).

The following peer reviewed publications have

resulted from this project:

• 2020, P. Dera, E. Bruffey III, G.J. Finkelstein,

C. Kelly, A. Gigante, H. Hagemann, G. Severa,

Synthesis, Characterization, and Crystal

Structures of Two New Manganese

Aceto EMIM Ionic Compounds with Chains

of Mn2+ Ions Coordinated Exclusively by

Acetate, ACS Omega, Vol. 5, Issue 25, pp.

15592-15600. (Open Access: PDF)

Figure 1.


Development of Novel Air Filtration Materials

http://dx.doi.org/10.1021/acsomega.0c01820





https://pubs.acs.org/doi/pdf/10.1021/acsomega.0c01820



• 2018, G. Severa, J. Head, K. Bethune, S. Higgins,

A. Fujise, Comparative studies of low

concentration SO2 and NO2 sorption by

activated carbon supported [C2mim][Ac] and

KOH sorbents, Journal of Environmental

Chemical Engineering, Vol. 6, Issue 1, pp. 718-

727.

• 2015, G. Severa, K. Bethune, R. Rocheleau, S.

Higgins, SO2 sorption by activated carbon

supported ionic liquids under simulated

atmospheric conditions, Chemical Engineering

Journal, Vol. 265, pp. 249-258.

Figure 2. EDS analyses of Fe4(OAc)10[C2mim]2 material

(a) as synthesized (b) after SO2 absorption, showing

intense presents of sulfur peaks (c) after SO2 desorption

at 90 °C, showing minute presence of sulfur species.




(a)

(b)

(c)

https://dx.doi.org/10.1016/j.jece.2017.12.020




http://dx.doi.org/10.1016/j.cej.2014.12.051






OBJECTIVE AND SIGNIFICANCE: This project’s

objective is the development of air filtration materials

that are capable of regeneration through UV light

exposure. These materials would have application to

purify air for stationary and vehicle fuel cell power

plants. Since these materials only require UV light for

regeneration, ambient sunlight could serve to

regenerate the materials, reducing energy or toxic

material demand and use in Hawaiʻi.

BACKGROUND: A novel method for regenerating air

filtration material through photocatalysis is reported

herein. In this study, titanium dioxide (TiO2) and

graphene oxide is covalently bonded to the surface of

granular activated carbon to form a uniform nano-

scale coating using nitric acid pretreatment and a

hydrothermal reaction. Coupling with graphene oxide

has also been shown to activate TiO2 under longer

wavelengths of visible light. Graphene oxide was

utilized in this study to enhance the efficiency of TiO2

and the allow the free radicals produced under UV

radiation to scavenge surface bonded air

contaminants, SO2 molecules in this case. A custom

air filtration test bed was used to expose air

contaminated with SO2 to the novel air filtration

materials. The test bed allowed the characterization of

the adsorption capacity of the novel air filtration

materials. After adsorption capacity was determined,

the material was submerged in an aqueous solution

and exposed to UV radiation. During that time, the

UV light is theorized to produce free radicals from

interaction with the TiO2, those free radicals are then

absorbed by the electron sink of the graphene oxide,

at which point the free radicals scavenge and attack

the nearest SO2 surface bond, thus releasing SO2 from

the surface and regenerating the surface so that the

material can be reused as an air filtration material.

PROJECT STATUS/RESULTS: Hydrothermal

synthesis of TiO2/graphene oxide coated activated

carbon was shown effective in producing a nanoscale,

uniform coating of TiO2 onto the surface of oxidized

activated carbon. Nitric acid (HNO3) pretreatment

was necessary to ensuring complete surface coverage

by increasing the surface carboxyl groups on

activated carbon. Presence of TiO2 decreased the

adsorption capacity of pure activated carbon from

0.139 to 0.075 g SO2/g TiO2/graphene oxide coated

activated carbon, corresponding to a 46% drop.

Photocatalytic oxidation and water regeneration

contributed to the overall regeneration of

TiO2/graphene oxide coated activated carbon. Water

regeneration provided a significant effect where a

67% regeneration efficiency was able to be obtained

without any UV exposure. When exposed to UV

light, an even higher regeneration efficiency of 87%

was achieved and the respective photocatalytic

mechanisms were speculated. The results from this

study (Figure 1) demonstrate the technical feasibility

of photocatalytic enhanced regeneration.

Figure 1. Initial and regenerated breakthrough capacity

of TGAC with and without UV exposure.


Contact: Godwin Severa, [email protected];




Regenerative Air Filtration Materials





OBJECTIVE AND SIGNIFICANCE: The goal of this

research project is to develop and demonstrate a

building energy analysis process that can be used

during early design phases at multiple transit-oriented

development (TOD) sites located along Oʻahu’s light

rail line. This helps Hawaiʻi meet its clean energy

goals; through reduced energy use in buildings,

increased energy security and resiliency, and a better

quality of life for residents.

BACKGROUND: HNEI has worked closely over the

years with the University of Hawaiʻi’s School of

Architecture’s Environmental Research and Design

Lab (ERDL) to conduct energy efficiency research.

Under this project, ERDL is collaborating with the

University of Hawaiʻi’s Community Design Center

(UHCDC), the developers of multi-family residential

building conceptual designs for the State Office of

Planning in a project called the “Waipahu Transit

Oriented Development Collaboration: Proof of

Concept Research, Planning, and Design Study.”

At the start of this project, the Center’s current TOD

planning process did not include quantitative targets

for building energy use or for on-site renewable

energy generation. Design teams lacked specific

guidance to design beyond the building energy code.

ERDL is collaborating with the UHCDC to bridge

these gaps by providing energy efficient design

processes and natural daylighting strategies.

The results of this process are intended to inform

designers, developers, and the State with specific

guidance on which building features will provide the

biggest impact on the energy performance, peak

loads, energy cost, building operating emissions, and

annual energy consumption.

The team set out to create a whole-building energy

model representative of future development of five-

story multi-family buildings in Waipahu, Hawaiʻi of

approximately 20,000ft².

In addition to the energy analysis, the team conducted

detailed thermal comfort modeling to evaluate the

applicability of passive cooling and/or mixed mode

operation of the air conditioning systems in the

residential units. The thermal comfort modeling

considered both current and future weather

predictions associated with various climate change

projections.

Figure 1. TOD Site, Waipahu. (Photo Credit: UHCDC)


Benchmarks: Based on existing benchmarks, new

condo/multifamily projects designed and built to the

current energy code (IECC 2015) perform similar to

many existing condo/multifamily developments in

Hawaiʻi. The energy simulations show that:

1. Designing to the IECC 2015 code can be

achieved without additional effort and

designers/building operators have the tools to

achieve built performance; and

2. Driving building energy consumption down will

take more than code minimum design.

The impact of combining various packages of energy

conservation measures are described below. For

additional detail, please refer to the final project

report (linked on the following page).

Baseline Modeling: Using computer simulation and

modeling, the team identified air conditioning (AC),

domestic hot water, lighting, and equipment as the

major energy end uses in a condo/multifamily

residential building making them appropriate targets

for advanced design.

Energy Analysis: The team demonstrated that

building with air conditioning can be designed to

reduce annual energy use by 29-61% compared to an

IECC 2015 code minimum building.

Hawaiʻi Natural Energy Institute Research Highlights Energy Efficiency & Transportation

Building Energy Reduction in Transit-Oriented Development Areas



The team modeled thousands of combinations of

energy and design features that include building

envelope and internal occupant loads. In addition to

AC, domestic hot water and lighting, occupant plug

loads, ventilation, window-to-wall ratio/glass, and

glazing types were the biggest factors that influence

energy performance.

Net Zero Energy (NZE) Targets: Buildings that are

2 stories or less can meet NZE targets. Taller

buildings (over 3 or 4 stories) designed to IECC 2015

code minimum prescriptive requirements cannot

achieve NZE due to insufficient roof area. In order for

high density buildings to meet the NZE goal, off-site

solar generation is needed.

Peak Cooling: Peak cooling demand can be reduced

by providing minimum ventilation, effective building

orientation, reduction of window area, increased

exterior shading of windows, and use of high

performance glass.

Peak Electrical Demand: Peak electrical demand

can be reduced by not installing AC or using high

efficiency AC when installed, with lower window-to-

wall ratio, higher shading ratio, and better window

performance. Photovoltaic panels and on-site battery

storage can shave the peak electrical demand.

Thermal Comfort: Historic climate data shows that

comfort can be achieved without mechanical cooling.

With ceiling fans and air movement, thermal comfort

can be increased to 96.4% of the year (based on the

ASHRAE 55 adaptive thermal comfort benchmark).

For reference, a typical conditioned office space is

considered properly designed when comfort targets

are achieved 98% of the year.

Even under optimistic future weather scenarios where

global temperature rise is muted (through reduction in

global greenhouse gas emissions), the passively

cooled space in Hawaiʻi will struggle to meet an

acceptable level of comfort throughout the year (more

than 90% comfortable). We would encourage

developers and designers to design for passive

cooling and provide provisions for future installation

of AC. The findings may also encourage the State to

consider more stringent energy targets which would

mitigate climate change and decrease the need for

future AC.

The final project report “University of Hawai’i

Whole-Building Energy Modeling for Future TOD

Areas” provides guidance to architects, engineers,

and professional designers in sufficient detail to allow

the methodologies be replicated when designing

future buildings in Hawaiʻi.


Special Fund



https://www.hnei.hawaii.edu/wp-content/uploads/UH-Whole-Building-Energy-Modeling-for-Future-TOD-Areas.pdf







this collaboration between the School of

Architecture’s Environmental Research and Design

Lab (ERDL) and the Hawai‘i Natural Energy Institute

(HNEI) is to provide technical support to the

Department of Hawaiian Home Lands (DHHL) and

two sets of their design/builders (Gentry; Habitat for

Humanity using a Honsador packaged design) to

improve comfort and energy efficiency of homes built

in their neighborhoods. The lessons learned can be

applied to future houses constructed in this climate

zone offering the opportunity to furgher reduce

Hawai‘i’s dependence on imported oil and reduce

greenhouse gas emissions.

Specific objective included:

1. Characterize the energy performance of typical

single-family homes built on lands administered

by DHHL.

2. Evaluate Building Energy Optimization Tool

(BEopt) software for its ability to estimate

relative performance of design options in terms of

site and source energy use, greenhouse gas

emissions, and thermal comfort.

3. Evaluate the ease of use of performance

simulations for detached residential design as a

flexible compliance pathway for the new Hawai‘i

State Energy Code based on International Energy

Conservation (IECC) 2015 and create models that

are minimally compliant to this code for the three

DHHL house types.

4. Calibrate the computational models against the

actual monitored energy use and temperatures

gathered from the existing houses.

5. Identify and quantify potential future design

strategies to exceed the new energy code and

improve thermal comfort.

6. Estimate the size of a photovoltaic array that

would achieve net-zero site energy.

7. Communicate these design strategies to DHHL,

the designers, and the builders for consideration

in future thousands of homes planned for

development.

8. Train advanced-level architecture and

engineering students, who are the design

professionals of tomorrow in building

monitoring, data analysis, and computer building

performance simulation.

BACKGROUND: A key function of DHHL is to

facilitate housing for native Hawaiian beneficiaries.

In the past 20 years, DHHL has built over 2,590

homes. It currently owns over 200,000 acres of land

on which it plans to construct another 875 homes over

the next 5 years. DHHL is the only housing developer

in Hawai‘i dedicated to providing new homes to

Hawaiian families. Historically, the homes have been

adequate and affordable, but DHHL has not provided

aggressive standards for building performance

beyond code and there has been no post-occupancy

work done to evaluate the energy performance or the

level of occupant comfort in the various house types

that have been constructed and occupied.

This study demonstrates how to improve the design

of three typical house types in Hawai‘i: fully air-

conditioned, partially air-conditioned, and naturally

ventilated (no air-conditioning). It was conducted

from June 2017 to April 2019 and consisted of three

components: monitoring existing houses; creating

energy simulation models; and making design

recommendations. The monitored houses, located in

the DHHL neighborhood of Kaneheli in Kapolei,

Oʻahu, were built between 2009 and 2017, when the

Hawai‘i energy code was based on the IECC 2006

energy code. A team of researchers at ERDL used

construction documents, field notes, and other

information to create energy simulation models of the

three house types. The houses were sub-metered for a

year and the data were used to validate the energy

models. These three existing-house models were

modified to be minimally compliant to the new

Hawai‘i energy code based on IECC 2015. Some

features were upgraded and others were downgraded

to minimally meet the code.

Three existing house types were studied: centrally air-

conditioned; partially air-conditioned; and naturally

ventilated (no air-conditioning). For each house type,

whole building energy models representing the

following cases were compared: 1) existing house; 2)

house minimally compliant with IECC 2015; 3)

sensitivity studies for individual design variables; 4)

house with combined energy efficiency measures;

and 5) house with on-site renewable energy

generation for net-zero energy performance.

The IECC 2015 models were used as a baselines to

compare how different energy conservation measures


Energy Efficient Home Design: Department of Hawaiian Home Lands



(ECMs) would individually affect the predicted

annual energy consumption. A combination of ECMs

were then selected by the research team to create a

“combined strategy” model for each house type. The

simulation models for the naturally ventilated house

were also assessed for thermal comfort.

PROJECT STATUS: This project was substantially

completed by November 2019, although disseminatio

of the results continued into 2020 with:

• Preparation of an abbreviated summary of results

targeting architects and design professionals, and;

• Preparation of peer reviewed paper “Going

Beyond Code: Monitoring Disaggregated

Energy and Modeling Detached Houses in

Hawai‘i”, published in the Buildings journal.

Overall, this initiative successfully:

• Trained UH system students in energy

monitoring and building simulation;

• Resulted in quantified recommendations for

design and operation of high-performance and

net-zero site-built and packaged housing units;

• Quantified the savings from energy efficient and

net zero options for 1,000 site-built and packaged

homes, and;

• Developed building simulation models to

evaluate multiple building scenarios.

Additionally, the investigation into the energy

consumption of typical DHHL building types has

benefits for the general understanding of residential

building strategies in Hawai‘i and this climate zone

and supports DHHL’s mission of providing

affordable housing over its full life-cycle.

SUMMARY RESULTS: In a hot and humid climate,

thermal comfort is a major driver in determining the

energy consumption of a home and the satisfaction of

the occupants. For fully air-conditioned homes,

cooling is the single largest end-use of energy: 40%

to 54% of annual consumption for homes in this

study. For naturally ventilated homes, improving

thermal comfort will improve the occupants’

experience and reduce the liklihood that air-

conditioning will be retrofitted into the house.

Based on the parametric analyses, the team selected

the energy efficiency measures at the point of

diminishing returns and anticipated acceptability by

builders and residents. These were inputs to an energy

model named “Combined Measures” for each house

type. The selected measures and their individual and

combined annual energy reductions as compared to

the IECC 2015 base case are listed below.

The results of this study was summarized in the

technical report “Methods for Establishing and

Validating Architectural Models to Analyze

Building Performance of Existing Conditions and

Simulated Design Options for Three Department

of Hawaiian Homeland Residential Buildings in

Kapolei, O‘ahu, Hawai‘i”.

Additional project summary sources: School of

Architecture Environmental Research and Design

Lab


Special Fund



http://dx.doi.org/10.3390/buildings10070120




https://www.hnei.hawaii.edu/wp-content/uploads/DHHL-Methods-for-Establishing-and-Validating-Architectural-Models.pdf










this multi-year project is to understand energy

performance and operation of net zero energy, mixed

mode buildings in tropical climate and to use the

buildings as real-world research facilities for the

study of energy efficient building features and control

strategies. The specific objectives of the current work

are to measure and evaluate indoor air quality,

particularly CO2, in manually operated mixed mode

buildings. High levels of CO2 can cause drowsiness,

absenteeism, and poorer student performance.

BACKGROUND: Two unique energy efficient, net

zero energy buildings constructed on the University

of Hawaiʻi at Mānoa campus serve as platforms for

energy, comfort, and controls strategy research. Since

2016, HNEI has been extensively monitoring these

mixed-mode Project FROG structures to gain insight

into their performance.

The buildings were designed to be naturally

ventilated with openable windows that allows air to

flow through the room. On-Demand HVAC control

prevents the room from being air conditioned

continuously at night or when classroom capacity

factor is below 60% during the day. With the

adjustable ceiling fans, the mixed mode buildings are

comfortable for most of the year without the air

conditioning running. The buildings are also outfitted

with photovoltaic systems that generate more power

than they consume.

The current research focuses on observing and

characterizing CO2 levels in the mixed mode

buildings and understanding the influence of window

operation. As part of this project, HNEI developed a

sensor providing the building occupants real-time

feedback on CO2 levels, including a cue to take action

to increase fresh air.

From an energy perspective, these buildings serve as

models for energy efficient construction with highly

insulated roof and walls, high performance low E

glazing, ceiling fans, LED lighting with daylight

controls, and orientation to prevent solar heat gain

through the windows.

In addition, the research platforms serve as beta test

sites for innovative controls and sensor research

experiments including:

• Real time CO2 indicators

• Automated ceiling fan controls

• Innovative occupancy sensing device

• Unique hi-res energy monitoring system

• Unique power quality monitoring system

• Deployed a thermal comfort perception kiosk

PROJECT STATUS/RESULTS: The Project FROG

buildings continue to serve as functioning classrooms

for both high school and university classes. In this

ongoing project, we observed that CO2 levels can

exceed recommended levels, occasionally by a factor

of two. User awareness and training are imperative to

properly operate in the mixed mode. Building

decisions are made every day by the instructors that

impact the indoor air quality of a mixed mode

building. Operation of windows, ceiling fans, and air

conditioning are judiciously used to create healthy

indoor air quality.

This project will be completed in December 2020.

Figure 1. UH Mānoa Project FROG buildings.





Project FROG Net Zero, Mixed Mode Buildings





TECHNICAL REPORTS:

1. Net Zero Energy Test Platform Performance Comprehensive Analysis, MKThink, March

2016


1. 2020, S. Cerri, A. Maskrey, E. Peppard, Retaining a healthy indoor environment in on-

demand mixed-mode classrooms, Developments in the Built Environment, Vol. 4, Paper

100031. (Open Access: PDF)

2. 2018, A.J. Maskrey, S. Cerri, E. Peppard, Second Generation ZNE: Inheriting the Good

Genes, Proceeding of ACEEE Summer Study on Energy Efficiency in Buildings Conference,

Panel 10: Net Zero: Moving Beyond 1%, Article 10.

3. 2016, A.J. Maskrey, S. Cerri, E. Peppard, M. Miller, S. Uddenberg, Positively net zero: case

study of performance simulation and hitting the targets, Proceeding of the ACEEE Summer

Study on Energy Efficiency in Buildings Conference, Panel 10: Net Zero, Net Positive, Article

10-1001.

PRESENTATIONS:

1. 2018, A.J. Maskrey, S. Cerri, E. Peppard, Next Generation ZNE: Inheriting the Good Genes,

Presented at the ACEEE Summer Study on Energy Efficiency in Buildings, Panel 10: Net Zero:

Moving Beyond 1%, Pacific Grove, California, August 12-17.

http://www.hnei.hawaii.edu/wp-content/uploads/Net-Zero-Energy-Test-Platform-Performance-Comparative-Analysis.pdf

http://dx.doi.org/10.1016/j.dibe.2020.100031

http://dx.doi.org/10.1016/j.dibe.2020.100031

https://www.sciencedirect.com/science/article/pii/S2666165920300272/pdfft?md5=26e76548e22b63de48d600a3595ba536&pid=1-s2.0-S2666165920300272-main.pdf

http://aceee.org/files/proceedings/2018/index.html#/paper/event-data/p309

http://aceee.org/files/proceedings/2018/index.html#/paper/event-data/p309

http://aceee.org/files/proceedings/2016/data/papers/10_1001.pdf

http://aceee.org/files/proceedings/2016/data/papers/10_1001.pdf

http://www.hnei.hawaii.edu/wp-content/uploads/2018-ACEEE_Next-Generation-NZE-Inheriting-the-Good-Genes.pdf




this project is to develop and test an adaptive lighting

system, based on novel Light Detection and Ranging

(LIDAR) sensor, that has the potential to significantly

enhance security and dramatically reduce energy use

and maintenance costs in high-security Naval

installations.

BACKGROUND: The adaptive lighting project is a

collaboration between HNEI, the California Lighting

and Technology Center (CLTC) at University of

California, Davis, and the Navy Facilities

Engineering Command (NAVFAC) Hawaiʻi.

Adaptive Lighting is the term describing a wide range

of lighting solutions that adjust to changing

environmental conditions, indoor or out. Adaptive

lighting intensity can rise and fall with ambient light

and occupancy while color rendering index and

temperature can be adjusted to conditions defined by

the end-use criteria.

In order to provide proof-of-concept and gain wider

acceptance, this demonstration project will study the

design, deployment, and impact of a unique wireless

networked adaptive lighting solution for exterior

lighting. Traditional security lighting, with long hours

of uniformity, wastes energy unnecessarily and may

reduce the security effectiveness in some

applications. Sensor-based dynamic lighting adds

conspicuous visual cues to enhance security

effectiveness. Adaptive lighting can save from 50-

70% of exterior lighting energy and has the potential

to become an effective security measure as well.

PROJECT STATUS/RESULTS: In this research project,

an adaptive lighting strategy is being piloted with

exterior lighting fixtures on four Oʻahu buildings –

two NAVFAC buildings located on the Joint Base

Pearl Harbor Hickam and two stand-alone classrooms

at the University of Hawaiʻi at Mānoa (UHM). The

exterior lighting levels will be variable, operating at

full intensity when there is activity detected near the

structures at night. With no motion detected, the

fixtures will dim down to 30%, providing enough

light for security purposes. LIDAR sensors send out

laser signals that when reflected back trigger an

action, specifically a signal to ramp the fixtures up to

100%. Sensors are positioned on these buildings to

create a 360 degree horizontal detection zone,

sensitive to any motion that crosses the beam’s path.

The second significant goal of this project is to test a

wireless networking system that will synchronize the

ramping up of all the fixtures simultaneously. When

one sensor is triggered, all of the fixtures connected

to the network will activate simultaneously. Not only

does this prevent a visually annoying checkerboard

effect with fixtures triggering at different times, but

site security is improved with the visual

“announcement” made when motion is detected and

the lights ramp immediately up from dim to 100%.

The sensors and monitoring equipment collected data

between January and July 2020. This data is currently

being evaluated.

The project was originally contracted from January

2019 to June 2020, however, delays due to the

coronavirus resulted in a no-cost extension to June

2021.

Figure 1. UHM FROGs with LIDAR sensor and

fixtures.





Adaptive Lighting and Energy Efficient Security Strategy




OBJECTIVE AND SIGNIFICANCE: The Thermal

Comfort Portal (http://hnei.hidoe-thermal-

comfort.4dapt.com) is a web-based research tool

developed for the Hawaiʻi Department of Education

(HIDOE) to provide resources for design and

implementation of their heat abatement program. In

addition to providing monitored climate and building

data, the portal includes recommendations about heat

abatement and thermal comfort strategies and

solutions for consumer and professional use. Its

objective is to expand program participation to the

greater sustainable design community, who could

offer abatement solutions during design and/or

implementation of heat mitigation strategies.

BACKGROUND: Many of the public schools in

Hawaiʻi do not have space conditioning, nor do they

have access to weather data that could inform

decisions about activities impacted by weather in

school facilities. Under this project, the Hawaiʻi

Natural Energy Institute (HNEI) is providing HIDOE

with the technical resources and expertise to support

the delivery of energy and weather data that enables

researchers, the community, and design professionals

to make data-driven decisions for designs and

resource allocation.

Publicly released in November of 2017, HNEI has

hosted the Thermal Comfort Portal as a research

resource for microclimatic data across Hawaiʻi.

Specific thermal performance of public schools are

also available on the website. HNEI supports public

participation and outreach by hosting the portal on its

website. The design firms MKThink and Roundhouse

One developed and constructed the Thermal Comfort

Portal on behalf of the HIDOE and continue to

provide back-end infrastructure support.

PROJECT STATUS/RESULTS: The HIDOE Thermal

Comfort Portal continues to be supported on the

HNEI website. HIDOE continues both its Heat

Abatement Program as well as its Cool Classrooms

air conditioning strategies.

This project is ongoing and HNEI’s hosting of the

portal will continue through December 2020.


Special Fund




State of Hawaiʻi Department of Education: Thermal Comfort Portal Web Hosting

Figure 1. A screenshot of the Thermal Comfort Portal,

showing Hokulani Elementary School’s outdoor

environmental data and classroom temperature data.

Figure 2. A screenshot of the Thermal Comfort

Portal, showing Hokulani Elementary School’s

indoor temperature and outdoor temperature heat

map.

http://hnei.hidoe-thermal-comfort.4dapt.com/

http://hnei.hidoe-thermal-comfort.4dapt.com/

http://www.hawaiipublicschools.org/ConnectWithUs/Organization/Offices/FacilitiesandOperations/FutureSchoolsNow/Pages/Heat-Abatement.aspx

http://www.hawaiipublicschools.org/ConnectWithUs/Organization/Offices/FacilitiesandOperations/FutureSchoolsNow/Pages/Heat-Abatement.aspx





this research is to develop a thorough understanding

of the baseline oceanographic conditions at the

proposed site of the Honolulu Seawater Air

Conditioning (SWAC) system, and ultimately to use

these data to assess the environmental impacts of the

operation of the SWAC system. The district-scale

system will be the largest of its kind in a tropical

environment.

BACKGROUND: Seawater air conditioning is a type of

renewable energy that utilizes deep, cold seawater in

a heat-exchange system to cool a freshwater loop. The

cold fresh water will then circulate to buildings and

act as air conditioning coolant, thereby providing

nearly carbon-neutral air conditioning. After the deep

seawater is warmed in the heat exchange process, it

will be released back to the ocean via diffuser.

In the proposed Honolulu SWAC system, deep

seawater will be drawn from 500 m and released via

diffuser at 100-140 m. Seawater at 500 m has

significantly different characteristics than seawater at

the diffuser depth, including nutrient concentrations

that are higher by several orders of magnitude. The

input of high-nutrient water could cause changes in

food web dynamics.

PROJECT STATUS/RESULTS: Since 2012, we have

characterized the oceanographic environment with

deployments of long-term moorings, water column

profiles, and water samples at both the intake (500 m)

and proposed release (100-140 m) locations. Results

have indicated that the plume of high-nutrient deep

seawater may sink below the lit region of the ocean

where phytoplankton grow (photic zone), reducing

the potential environmental impacts. However, the

depth of the plume release is at an area of rapid

density change, and it is also possible that the plume

may spread horizontally along the density surface and

remain near the base of the photic layer. During

strong wind events, deep mixing may bring the

nutrient-rich water into the shallow photic zone,

creating the possibility of a phytoplankton blooms

(Comfort, 2015). Observations of the mesopelagic

boundary community’s daily across-slope migration

indicated that the mid-trophic level organisms of this

ecosystem will interact directly with the plume waters

during their daily migration (Comfort, 2017).

Currently, monitoring efforts are ongoing and the

temporal and spatial dynamics of phytoplankton at

the proposed SWAC site are being investigated. Cell

count data reveal higher concentrations of

Synechococcus and lower Prochlorococcus at the

nearshore release site than offshore near the intake

site, which could be related to island effects of light

availability and nutrients in the upper water column.

We are currently characterizing the seasonality of

phytoplankton which will provide the necessary

baseline to assess if the operation of SWAC alters

concentrations beyond natural fluctuations. Nutrients

and phytoplankton counts were tightly correlated,

suggesting that an input of nutrients from deep water

to the photic zone from the SWAC system would

alter the plankton dynamics of the region.

This project has produced the following publications:

• 2017, C.M Comfort, et al., Observations of the

Hawaiian Mesopelagic Boundary Community

in Daytime and Nighttime Habitats Using

Estimated Backscatter, AIMS Geosciences,

Vol. 3, Issue 3, pp. 304-326.

• 2015, C.M. Comfort, et al., Environmental

Properties of Coastal Waters in Mamala Bay,

Oʻahu, Hawaiʻi, at the Future Site of a

Seawater Air Conditioning Outfall,

Oceanography, Vol. 28, Issue 2, pp. 230-239.



Contact: Margaret McManus, [email protected];

Christina Comfort, [email protected]



Seawater Air Conditioning Environmental Monitoring

https://dx.doi.org/10.3934/geosci.2017.3.304




https://dx.doi.org/10.5670/oceanog.2015.46








OBJECTIVE AND SIGNIFICANCE: The main objective

of this demonstration project is to develop and

evaluate the performance of novel algorithms to

optimize the charge/discharge of shared fleet

vehicles. Project experience and results will inform

University consideration of options such as the

electrification of fleet vehicles, advanced car share

applications, integration of distributed renewable

energy resources on campus, and the optimal

management of campus energy use and cost

containment.

BACKGROUND: HNEI is collaborating with Hitachi

Limited and IKS Co., Ltd. on a technology

development, test, and demonstration project to

install two bi-directional electric vehicle (EV)

chargers (Hybrid-PCS on the campus of the

University of Hawaiʻi at Mānoa, at two designated

parking stalls indicated by the red rectangle in Figure

1, located adjacent to the Bachman Annex 6 building

indicated by the orange rectangle in Figure 1.

Figure 1. Location of bi-directional EV chargers.

The new control algorithms will ensure that the

shared vehicles are efficiently assigned and readily

available for transport needs, while providing

ancillary power and energy services by virtue of

charging or use of the stored energy in the vehicle

batteries to benefit both the customer (UH Mānoa)

and possibly the operational needs of the local grid

operator (Hawaiian Electric).

The two EVs will be used by designated university

personnel through a limited-user pool car sharing

system via a smart phone/web-based application

made available to the drivers. The EVs are planned to

replace the present use of two existing UH gasoline-

powered vehicles for the duration of this multi-year

demonstration.

Figure 2. Functional system diagram.

This project is being conducted by HNEI’s

GridSTART team. The team is developing a web-

based software suite for EV drivers to sign-out the

cars for use and will design, code, and integrate

software to optimize charge/discharge schedules for

the EVs, balancing transport needs and power/energy

benefits for the University (e.g., time-of use tariff

rates, building load shaping, smart EV charging, etc.),

and possibly grid ancillary services. The Hybrid-PCS

can also incorporate solar PV power as a source of

energy for EV charging. The optimization software

will incorporate in-house developed state-of-the-art

solar forecasts and maximization of solar energy as

the preferred source for EV charging.

PROJECT STATUS/RESULTS: An EV has been

purchased and HNEI has taken delivery of the first

Hybrid-PCS for the project. Engineering design

drawings for charger installation are complete. The

procurement of construction services and equipment

needed to install the bi-directional EV chargers on

campus is underway. EV charge/discharge control

algorithms and EV car scheduling software is under

development, along with plans for hardware-in-the-

loop testing of controls and communications.

Delivery of the second Hybrid-PCS is expected in

February 2021, with project installation and go-live

to follow.

Funding Source: Office of Naval Research; Hitachi

Advanced Clean Energy Corporation




Bi-Directional EV Charging Demonstration Project


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